diff --git a/README.md b/README.md
index 13ed1d1..5a78317 100644
--- a/README.md
+++ b/README.md
@@ -24,3 +24,13 @@ TermRemoteCtl is a personal remote coding controller for one Windows workstation
 - `flutter test apps/mobile_app/test`
 - `flutter test apps/mobile_app/integration_test`
 - The Flutter `integration_test` suite may still require a supported local runtime target or device on the machine running it.
+
+## Terminal Truth Source
+
+The stable product path uses one rendering truth source:
+
+- backend `restore` plus `output` provide the durable terminal data
+- frontend `xterm` is the only visible renderer on the mainline
+- local mobile snapshots are provisional cache only
+
+Backend `screen_snapshot`, `screen_patch`, and `screen_sync` are experiment-only paths. They must stay behind an explicit opt-in switch and must not drive the default product terminal.
diff --git a/apps/mobile_app/lib/core/network/agent_socket_client.dart b/apps/mobile_app/lib/core/network/agent_socket_client.dart
index 82eb082..e2be05e 100644
--- a/apps/mobile_app/lib/core/network/agent_socket_client.dart
+++ b/apps/mobile_app/lib/core/network/agent_socket_client.dart
@@ -13,24 +13,14 @@ class AgentSocketClient {
     );
   }
 
-  Map<String, dynamic> buildAttachMessage(String sessionId) => <String, dynamic>{
-        'type': 'attach',
-        'sessionId': sessionId,
-      };
+  Map<String, dynamic> buildAttachMessage(String sessionId) =>
+      <String, dynamic>{'type': 'attach', 'sessionId': sessionId};
 
   Map<String, dynamic> buildInputMessage(String input) => <String, dynamic>{
-        'type': 'input',
-        'input': input,
-      };
+    'type': 'input',
+    'input': input,
+  };
 
   Map<String, dynamic> buildResizeMessage(int columns, int rows) =>
-      <String, dynamic>{
-        'type': 'resize',
-        'columns': columns,
-        'rows': rows,
-      };
-
-  Map<String, dynamic> buildScreenSyncMessage() => <String, dynamic>{
-        'type': 'screen_sync',
-      };
+      <String, dynamic>{'type': 'resize', 'columns': columns, 'rows': rows};
 }
diff --git a/apps/mobile_app/lib/features/terminal/terminal_page.dart b/apps/mobile_app/lib/features/terminal/terminal_page.dart
index eea852d..38c7e7d 100644
--- a/apps/mobile_app/lib/features/terminal/terminal_page.dart
+++ b/apps/mobile_app/lib/features/terminal/terminal_page.dart
@@ -22,9 +22,6 @@ import 'repeatable_terminal_key_button.dart';
 import 'terminal_interaction_controller.dart';
 import 'terminal_restore_payload.dart';
 import 'terminal_restore_decision.dart';
-import 'terminal_screen_patch.dart';
-import 'terminal_screen_state.dart';
-import 'terminal_screen_snapshot.dart';
 import 'terminal_session_coordinator.dart';
 import 'terminal_snapshot.dart';
 import 'terminal_snapshot_storage.dart';
@@ -154,7 +151,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
   String? _pendingHistorySeed;
   bool _receivedSocketFrame = false;
   bool _receivedRestorePayload = false;
-  bool _receivedScreenSnapshot = false;
   bool _historySeeded = false;
   bool _awaitingAttachReplayFrame = true;
   bool _awaitingReconnectRestore = false;
@@ -162,7 +158,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
   bool _showExpandedControls = false;
   _TerminalInputMode _inputMode = _TerminalInputMode.read;
   TerminalConnectionState? _lastConnectionState;
-  TerminalScreenState? _authoritativeScreenState;
 
   @override
   void initState() {
@@ -179,8 +174,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
       onFrame: _handleTerminalFrame,
       onRestore: _handleRestorePayload,
       onHistoryLoaded: _handleHistoryLoaded,
-      onScreenSnapshot: _handleScreenSnapshot,
-      onScreenPatch: _handleScreenPatch,
       viewportProvider: () => TerminalViewport(
         columns: terminal.viewWidth,
         rows: terminal.viewHeight,
@@ -354,6 +347,12 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     _terminalFocusNode.requestFocus();
   }
 
+  void _restoreEditFocusIfNeeded() {
+    if (_inputMode == _TerminalInputMode.edit) {
+      _terminalFocusNode.requestFocus();
+    }
+  }
+
   Future<void> _copySelectedOrVisibleText() async {
     final selection = _terminalViewController.selection;
     final selectedText = selection == null
@@ -397,11 +396,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     _receivedSocketFrame = true;
     _awaitingReconnectRestore = false;
     _cancelHistorySeedTimer();
-    if (_authoritativeScreenState != null) {
-      _scheduleSnapshotPersist();
-      return;
-    }
-
     terminal.write(frame);
     _scheduleSnapshotPersist();
   }
@@ -412,11 +406,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     _receivedRestorePayload = true;
     _awaitingReconnectRestore = false;
     _cancelHistorySeedTimer();
-    if (_authoritativeScreenState != null) {
-      _scheduleSnapshotPersist();
-      return;
-    }
-
     final combined = restore.screenText + restore.pendingInput;
     if (combined.isEmpty) {
       _scheduleSnapshotPersist();
@@ -435,43 +424,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     _scheduleSnapshotPersist();
   }
 
-  void _handleScreenSnapshot(TerminalScreenSnapshot snapshot) {
-    _awaitingAttachReplayFrame = false;
-    _receivedSocketFrame = true;
-    _receivedScreenSnapshot = true;
-    _awaitingReconnectRestore = false;
-    _cancelHistorySeedTimer();
-    _authoritativeScreenState = TerminalScreenState.fromSnapshot(snapshot);
-    final displayText = _authoritativeScreenState!.toDisplayText();
-    _resetTerminalForSnapshot();
-    if (displayText.isNotEmpty) {
-      terminal.write(displayText);
-    }
-    _historySeeded = _terminalHasVisibleContent;
-    _scheduleSnapshotPersist();
-  }
-
-  void _handleScreenPatch(TerminalScreenPatch patch) {
-    final currentState = _authoritativeScreenState;
-    if (currentState == null || !currentState.canApplyPatch(patch)) {
-      return;
-    }
-
-    _awaitingAttachReplayFrame = false;
-    _receivedSocketFrame = true;
-    _receivedScreenSnapshot = true;
-    _awaitingReconnectRestore = false;
-    _cancelHistorySeedTimer();
-    _authoritativeScreenState = currentState.applyPatch(patch);
-    final displayText = _authoritativeScreenState!.toDisplayText();
-    _resetTerminalForSnapshot();
-    if (displayText.isNotEmpty) {
-      terminal.write(displayText);
-    }
-    _historySeeded = _terminalHasVisibleContent;
-    _scheduleSnapshotPersist();
-  }
-
   void _handleHistoryLoaded(HistoryWindow history) {
     final seedText = _buildHistorySeedText(history.lines);
     if (seedText.isEmpty) {
@@ -490,8 +442,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
           connectionState == TerminalConnectionState.reconnecting) {
         _awaitingAttachReplayFrame = true;
         _receivedRestorePayload = false;
-        _receivedScreenSnapshot = false;
-        _authoritativeScreenState = null;
         if (connectionState == TerminalConnectionState.reconnecting) {
           _awaitingReconnectRestore = true;
           _receivedSocketFrame = false;
@@ -506,11 +456,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
   }
 
   void _scheduleHistorySeedIfNeeded() {
-    if (_receivedScreenSnapshot) {
-      _cancelHistorySeedTimer();
-      return;
-    }
-
     if (_receivedRestorePayload) {
       _cancelHistorySeedTimer();
       return;
@@ -575,12 +520,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     terminal.notifyListeners();
   }
 
-  void _resetTerminalForSnapshot() {
-    terminal.buffer.clear();
-    terminal.buffer.setCursor(0, 0);
-    terminal.notifyListeners();
-  }
-
   bool _shouldSuppressAttachReplay(String frame) {
     final normalizedFrame = _trimTrailingNewlines(
       _normalizeTerminalText(frame),
@@ -1064,12 +1003,6 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
                           onPressed: () =>
                               _setInputMode(_TerminalInputMode.edit),
                         ),
-                        Text(
-                          _inputMode == _TerminalInputMode.read
-                              ? 'Read mode prevents the terminal from taking focus.'
-                              : 'Edit mode keeps the terminal ready for typing.',
-                          style: Theme.of(context).textTheme.bodySmall,
-                        ),
                       ],
                     ),
                   ),
@@ -1228,7 +1161,7 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
 
   Widget _buildStatusRow(BuildContext context) {
     final mode = controller.isFollowingLiveOutput ? 'Live' : 'Scrollback';
-    final modeLabel = '$mode | ${controller.liveLines.length} lines';
+    final modeLabel = mode;
     return Wrap(
       key: const Key('terminal_status_summary'),
       spacing: 8,
@@ -1254,12 +1187,13 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
           icon: _statusIcon,
           color: _statusColor(context),
         ),
-        Text(
-          _coordinator.connectionStatus,
-          maxLines: 1,
-          overflow: TextOverflow.ellipsis,
-          style: Theme.of(context).textTheme.bodySmall,
-        ),
+        if (_connectionState != TerminalConnectionState.connected)
+          Text(
+            _coordinator.connectionStatus,
+            maxLines: 1,
+            overflow: TextOverflow.ellipsis,
+            style: Theme.of(context).textTheme.bodySmall,
+          ),
       ],
     );
   }
diff --git a/apps/mobile_app/lib/features/terminal/terminal_screen_snapshot.dart b/apps/mobile_app/lib/features/terminal/terminal_screen_snapshot.dart
index b41cb70..665f164 100644
--- a/apps/mobile_app/lib/features/terminal/terminal_screen_snapshot.dart
+++ b/apps/mobile_app/lib/features/terminal/terminal_screen_snapshot.dart
@@ -1,3 +1,4 @@
+/// Experiment-only model for the backend screen protocol.
 class TerminalScreenSnapshot {
   const TerminalScreenSnapshot({
     required this.sessionId,
@@ -51,7 +52,38 @@ class TerminalScreenSnapshot {
     final buffer = activeBuffer == 'alternate' && alternateBuffer != null
         ? alternateBuffer!
         : primaryBuffer;
-    return buffer.viewport.map((line) => line.text).join('\n');
+    final lines = List<String>.filled(rows, '');
+    for (final line in buffer.viewport) {
+      if (line.index >= 0 && line.index < lines.length) {
+        lines[line.index] = line.text;
+      }
+    }
+
+    return renderTerminalScreenText(
+      lines: lines,
+      cursorRow: cursorRow,
+      cursorColumn: cursorColumn,
+      cursorVisible: cursorVisible,
+    );
+  }
+
+  String toReplaySequence() {
+    final buffer = activeBuffer == 'alternate' && alternateBuffer != null
+        ? alternateBuffer!
+        : primaryBuffer;
+    final lines = List<String>.filled(rows, '');
+    for (final line in buffer.viewport) {
+      if (line.index >= 0 && line.index < lines.length) {
+        lines[line.index] = line.text;
+      }
+    }
+
+    return buildTerminalScreenReplay(
+      lines: lines,
+      cursorRow: cursorRow,
+      cursorColumn: cursorColumn,
+      cursorVisible: cursorVisible,
+    );
   }
 }
 
@@ -87,3 +119,119 @@ class TerminalScreenLine {
     );
   }
 }
+
+String renderTerminalScreenText({
+  required List<String> lines,
+  required int cursorRow,
+  required int cursorColumn,
+  required bool cursorVisible,
+}) {
+  var lastContentRow = -1;
+  for (var index = 0; index < lines.length; index += 1) {
+    if (_trimRight(lines[index]).isNotEmpty) {
+      lastContentRow = index;
+    }
+  }
+
+  final lastVisibleRow = _clampLastVisibleRow(
+    lines.length,
+    lastContentRow: lastContentRow,
+    cursorRow: cursorVisible ? cursorRow : -1,
+  );
+  if (lastVisibleRow < 0) {
+    return '';
+  }
+
+  return List<String>.generate(lastVisibleRow + 1, (row) {
+    final line = lines[row];
+    final trimmed = _trimRight(line);
+    if (!cursorVisible || row != cursorRow) {
+      return trimmed;
+    }
+
+    final targetWidth = cursorColumn.clamp(0, line.length);
+    if (targetWidth <= trimmed.length) {
+      return trimmed;
+    }
+
+    return line.substring(0, targetWidth);
+  }).join('\n');
+}
+
+String buildTerminalScreenReplay({
+  required List<String> lines,
+  required int cursorRow,
+  required int cursorColumn,
+  required bool cursorVisible,
+}) {
+  final lastContentRow = _findLastContentRow(lines);
+  final lastVisibleRow = _clampLastVisibleRow(
+    lines.length,
+    lastContentRow: lastContentRow,
+    cursorRow: cursorVisible ? cursorRow : -1,
+  );
+  final replay = StringBuffer()..write('\u001b[2J\u001b[H');
+
+  for (var row = 0; row <= lastVisibleRow; row += 1) {
+    replay.write('\u001b[');
+    replay.write(row + 1);
+    replay.write(';1H\u001b[2K');
+
+    final text = _trimRight(lines[row]);
+    if (text.isNotEmpty) {
+      replay.write(text);
+    }
+  }
+
+  if (cursorVisible && lines.isNotEmpty) {
+    final targetRow = cursorRow.clamp(0, lines.length - 1);
+    final targetColumn = cursorColumn.clamp(0, lines[targetRow].length);
+    replay.write('\u001b[');
+    replay.write(targetRow + 1);
+    replay.write(';');
+    replay.write(targetColumn + 1);
+    replay.write('H');
+  }
+
+  return replay.toString();
+}
+
+int _clampLastVisibleRow(
+  int lineCount, {
+  required int lastContentRow,
+  required int cursorRow,
+}) {
+  if (lineCount <= 0) {
+    return -1;
+  }
+
+  var lastVisibleRow = lastContentRow;
+  if (cursorRow >= 0) {
+    lastVisibleRow = lastVisibleRow > cursorRow ? lastVisibleRow : cursorRow;
+  }
+
+  if (lastVisibleRow < 0) {
+    return -1;
+  }
+
+  return lastVisibleRow >= lineCount ? lineCount - 1 : lastVisibleRow;
+}
+
+int _findLastContentRow(List<String> lines) {
+  for (var index = lines.length - 1; index >= 0; index -= 1) {
+    if (_trimRight(lines[index]).isNotEmpty) {
+      return index;
+    }
+  }
+
+  return -1;
+}
+
+String _trimRight(String value) {
+  var end = value.length;
+  while (end > 0 && value.codeUnitAt(end - 1) == 0x20) {
+    end -= 1;
+  }
+
+  return end == value.length ? value : value.substring(0, end);
+}
diff --git a/apps/mobile_app/lib/features/terminal/terminal_screen_state.dart b/apps/mobile_app/lib/features/terminal/terminal_screen_state.dart
index 112f8dc..4307d88 100644
--- a/apps/mobile_app/lib/features/terminal/terminal_screen_state.dart
+++ b/apps/mobile_app/lib/features/terminal/terminal_screen_state.dart
@@ -1,6 +1,7 @@
 import 'terminal_screen_patch.dart';
 import 'terminal_screen_snapshot.dart';
 
+/// Experiment-only state reducer for backend-authored screen snapshots and patches.
 class TerminalScreenState {
   const TerminalScreenState({
     required this.sessionId,
@@ -57,12 +58,16 @@ class TerminalScreenState {
   }
 
   bool canApplyPatch(TerminalScreenPatch patch) {
-    return sessionId == patch.sessionId && screenVersion == patch.baseScreenVersion;
+    return sessionId == patch.sessionId &&
+        screenVersion == patch.baseScreenVersion;
   }
 
   TerminalScreenState applyPatch(TerminalScreenPatch patch) {
     final nextPrimaryLines = List<String>.from(primaryLines, growable: false);
-    final nextAlternateLines = List<String>.from(alternateLines, growable: false);
+    final nextAlternateLines = List<String>.from(
+      alternateLines,
+      growable: false,
+    );
     final targetLines = patch.activeBuffer == 'alternate'
         ? nextAlternateLines
         : nextPrimaryLines;
@@ -96,6 +101,21 @@ class TerminalScreenState {
 
   String toDisplayText() {
     final lines = activeBuffer == 'alternate' ? alternateLines : primaryLines;
-    return lines.join('\n');
+    return renderTerminalScreenText(
+      lines: lines,
+      cursorRow: cursorRow,
+      cursorColumn: cursorColumn,
+      cursorVisible: cursorVisible,
+    );
+  }
+
+  String toReplaySequence() {
+    final lines = activeBuffer == 'alternate' ? alternateLines : primaryLines;
+    return buildTerminalScreenReplay(
+      lines: lines,
+      cursorRow: cursorRow,
+      cursorColumn: cursorColumn,
+      cursorVisible: cursorVisible,
+    );
   }
 }
diff --git a/apps/mobile_app/lib/features/terminal/terminal_session_coordinator.dart b/apps/mobile_app/lib/features/terminal/terminal_session_coordinator.dart
index 5eba66f..99dd211 100644
--- a/apps/mobile_app/lib/features/terminal/terminal_session_coordinator.dart
+++ b/apps/mobile_app/lib/features/terminal/terminal_session_coordinator.dart
@@ -9,8 +9,6 @@ import 'terminal_diagnostic_log.dart';
 import 'terminal_interaction_controller.dart';
 import 'terminal_output_payload.dart';
 import 'terminal_restore_payload.dart';
-import 'terminal_screen_patch.dart';
-import 'terminal_screen_snapshot.dart';
 import 'terminal_socket_session.dart';
 
 typedef CancelReconnect = void Function();
@@ -40,8 +38,6 @@ class TerminalSessionCoordinator extends ChangeNotifier {
     required this.sessionFactory,
     required this.onFrame,
     required this.onRestore,
-    this.onScreenSnapshot,
-    this.onScreenPatch,
     required this.viewportProvider,
     Uri? baseUri,
     this.onHistoryLoaded,
@@ -68,8 +64,6 @@ class TerminalSessionCoordinator extends ChangeNotifier {
   final TerminalSessionFactory sessionFactory;
   final void Function(String frame) onFrame;
   final void Function(TerminalRestorePayload restore) onRestore;
-  final void Function(TerminalScreenSnapshot snapshot)? onScreenSnapshot;
-  final void Function(TerminalScreenPatch patch)? onScreenPatch;
   final TerminalViewport Function() viewportProvider;
   final Uri baseUri;
   final void Function(HistoryWindow history)? onHistoryLoaded;
@@ -93,9 +87,6 @@ class TerminalSessionCoordinator extends ChangeNotifier {
   int? _lastSentColumns;
   int? _lastSentRows;
   int? _lastReceivedSequence;
-  int? _screenVersion;
-  bool _screenProtocolActive = false;
-  bool _screenSyncPending = false;
 
   bool get isLoadingOlderHistory => _isLoadingOlderHistory;
 
@@ -111,9 +102,6 @@ class TerminalSessionCoordinator extends ChangeNotifier {
     }
 
     final sessionGeneration = ++_sessionGeneration;
-    _screenProtocolActive = false;
-    _screenVersion = null;
-    _screenSyncPending = false;
 
     if (isReconnect) {
       controller.markReconnecting();
@@ -156,20 +144,6 @@ class TerminalSessionCoordinator extends ChangeNotifier {
 
           _handleRestore(restore);
         },
-        onScreenSnapshot: (snapshot) {
-          if (!_isCurrentSession(socketSession, sessionGeneration)) {
-            return;
-          }
-
-          _handleScreenSnapshot(snapshot);
-        },
-        onScreenPatch: (patch) {
-          if (!_isCurrentSession(socketSession, sessionGeneration)) {
-            return;
-          }
-
-          _handleScreenPatch(patch);
-        },
         onDisconnected: () {
           if (!_isCurrentSession(socketSession, sessionGeneration)) {
             return;
@@ -315,7 +289,8 @@ class TerminalSessionCoordinator extends ChangeNotifier {
   Future<void> _handleOutput(TerminalOutputPayload output) async {
     if (output.sequence > 0) {
       final lastReceivedSequence = _lastReceivedSequence;
-      if (lastReceivedSequence != null && output.sequence <= lastReceivedSequence) {
+      if (lastReceivedSequence != null &&
+          output.sequence <= lastReceivedSequence) {
         diagnosticLog?.add(
           'socket.output.stale',
           'seq=${output.sequence} last=$lastReceivedSequence',
@@ -340,14 +315,6 @@ class TerminalSessionCoordinator extends ChangeNotifier {
   }
 
   void _applyOutput(TerminalOutputPayload output) {
-    if (_screenProtocolActive) {
-      diagnosticLog?.add('socket.output.compat.skip', 'seq=${output.sequence}');
-      if (output.sequence > 0) {
-        _lastReceivedSequence = output.sequence;
-      }
-      return;
-    }
-
     diagnosticLog?.add('socket.frame.rx', output.chunk);
     controller.registerIncomingFrame();
     controller.applyFrame(output.chunk);
@@ -366,53 +333,14 @@ class TerminalSessionCoordinator extends ChangeNotifier {
     onRestore(restore);
   }
 
-  void _handleScreenSnapshot(TerminalScreenSnapshot snapshot) {
-    diagnosticLog?.add(
-      'socket.screen_snapshot.rx',
-      'screenVersion=${snapshot.screenVersion} sourceSeq=${snapshot.sourceSequence}',
-    );
-    _screenProtocolActive = true;
-    _screenVersion = snapshot.screenVersion;
-    _screenSyncPending = false;
-    if (snapshot.sourceSequence > 0) {
-      _lastReceivedSequence = snapshot.sourceSequence;
-    }
-    onScreenSnapshot?.call(snapshot);
-  }
-
-  void _handleScreenPatch(TerminalScreenPatch patch) {
-    diagnosticLog?.add(
-      'socket.screen_patch.rx',
-      'base=${patch.baseScreenVersion} next=${patch.screenVersion} sourceSeq=${patch.sourceSequence}',
-    );
-    if (_screenVersion != null && patch.baseScreenVersion != _screenVersion) {
-      _screenProtocolActive = false;
-      diagnosticLog?.add(
-        'socket.screen_patch.skip',
-        'expected=$_screenVersion actual=${patch.baseScreenVersion}',
-      );
-      if (!_screenSyncPending) {
-        _screenSyncPending = true;
-        _socketSession?.requestScreenSync();
-        diagnosticLog?.add('socket.screen_sync.request', session.sessionId);
-      }
-      return;
-    }
-
-    _screenProtocolActive = true;
-    _screenVersion = patch.screenVersion;
-    if (patch.sourceSequence > 0) {
-      _lastReceivedSequence = patch.sourceSequence;
-    }
-    onScreenPatch?.call(patch);
-  }
-
   Future<void> _loadHistory({bool loadOlder = false}) async {
     try {
       final payload = await apiClient.getSessionJournal(
         session.sessionId,
         limit: historyPageSize,
-        beforeSequence: loadOlder ? controller.historyWindow.oldestSequence : null,
+        beforeSequence: loadOlder
+            ? controller.historyWindow.oldestSequence
+            : null,
       );
       final history = _buildHistoryWindow(
         payload,
@@ -643,7 +571,8 @@ class TerminalSessionCoordinator extends ChangeNotifier {
         ? existing?.oldestSequence
         : items.first.sequence;
     final newestSequence =
-        existing?.newestSequence ?? (items.isEmpty ? null : items.last.sequence);
+        existing?.newestSequence ??
+        (items.isEmpty ? null : items.last.sequence);
 
     return HistoryWindow(
       lines: mergedLines,
@@ -657,9 +586,8 @@ class TerminalSessionCoordinator extends ChangeNotifier {
     final rawItems = (payload['items'] as List?) ?? const <dynamic>[];
     return rawItems
         .map(
-          (item) => _JournalItem.fromJson(
-            Map<String, dynamic>.from(item as Map),
-          ),
+          (item) =>
+              _JournalItem.fromJson(Map<String, dynamic>.from(item as Map)),
         )
         .toList(growable: false);
   }
diff --git a/apps/mobile_app/lib/features/terminal/terminal_socket_session.dart b/apps/mobile_app/lib/features/terminal/terminal_socket_session.dart
index cfdca13..5827151 100644
--- a/apps/mobile_app/lib/features/terminal/terminal_socket_session.dart
+++ b/apps/mobile_app/lib/features/terminal/terminal_socket_session.dart
@@ -9,8 +9,6 @@ import '../../core/network/agent_socket_client.dart';
 import '../sessions/session.dart';
 import 'terminal_output_payload.dart';
 import 'terminal_restore_payload.dart';
-import 'terminal_screen_patch.dart';
-import 'terminal_screen_snapshot.dart';
 
 typedef TerminalSocketTransportFactory =
     TerminalSocketTransport Function(Uri uri);
@@ -61,8 +59,6 @@ class TerminalSocketSession {
   Future<void> connect({
     required void Function(TerminalOutputPayload output) onOutput,
     required void Function(TerminalRestorePayload restore) onRestore,
-    void Function(TerminalScreenSnapshot snapshot)? onScreenSnapshot,
-    void Function(TerminalScreenPatch patch)? onScreenPatch,
     void Function()? onDisconnected,
   }) async {
     if (_transport != null || _subscription != null) {
@@ -93,14 +89,6 @@ class TerminalSocketSession {
           return;
         }
 
-        if (_handleScreenSnapshotFrame(message, onScreenSnapshot)) {
-          return;
-        }
-
-        if (_handleScreenPatchFrame(message, onScreenPatch)) {
-          return;
-        }
-
         final output = _decodeOutputFrame(message);
         if (output != null) {
           onOutput(output);
@@ -170,20 +158,9 @@ class TerminalSocketSession {
     }
 
     try {
-      transport.send(jsonEncode(socketClient.buildResizeMessage(columns, rows)));
-    } catch (_) {
-      _handleTransportClosed(transport);
-    }
-  }
-
-  void requestScreenSync() {
-    final transport = _transport;
-    if (transport == null) {
-      return;
-    }
-
-    try {
-      transport.send(jsonEncode(socketClient.buildScreenSyncMessage()));
+      transport.send(
+        jsonEncode(socketClient.buildResizeMessage(columns, rows)),
+      );
     } catch (_) {
       _handleTransportClosed(transport);
     }
@@ -227,53 +204,13 @@ class TerminalSocketSession {
     return false;
   }
 
-  bool _handleScreenSnapshotFrame(
-    String frame,
-    void Function(TerminalScreenSnapshot snapshot)? onScreenSnapshot,
-  ) {
-    if (onScreenSnapshot == null) {
-      return false;
-    }
-
-    try {
-      final decoded = jsonDecode(frame);
-      if (decoded is Map && decoded['type'] == 'screen_snapshot') {
-        onScreenSnapshot(
-          TerminalScreenSnapshot.fromJson(Map<String, dynamic>.from(decoded)),
-        );
-        return true;
-      }
-    } catch (_) {}
-
-    return false;
-  }
-
-  bool _handleScreenPatchFrame(
-    String frame,
-    void Function(TerminalScreenPatch patch)? onScreenPatch,
-  ) {
-    if (onScreenPatch == null) {
-      return false;
-    }
-
-    try {
-      final decoded = jsonDecode(frame);
-      if (decoded is Map && decoded['type'] == 'screen_patch') {
-        onScreenPatch(
-          TerminalScreenPatch.fromJson(Map<String, dynamic>.from(decoded)),
-        );
-        return true;
-      }
-    } catch (_) {}
-
-    return false;
-  }
-
   TerminalOutputPayload? _decodeOutputFrame(String frame) {
     try {
       final decoded = jsonDecode(frame);
       if (decoded is Map && decoded['type'] == 'output') {
-        return TerminalOutputPayload.fromJson(Map<String, dynamic>.from(decoded));
+        return TerminalOutputPayload.fromJson(
+          Map<String, dynamic>.from(decoded),
+        );
       }
 
       if (decoded is Map && decoded['type'] != null) {
diff --git a/apps/mobile_app/test/core/network/agent_socket_client_test.dart b/apps/mobile_app/test/core/network/agent_socket_client_test.dart
index 49e4e66..a1a9625 100644
--- a/apps/mobile_app/test/core/network/agent_socket_client_test.dart
+++ b/apps/mobile_app/test/core/network/agent_socket_client_test.dart
@@ -14,35 +14,18 @@ void main() {
   test('builds attach message for terminal sessions', () {
     final client = AgentSocketClient(Uri.parse('https://host:9443'));
 
-    expect(
-      client.buildAttachMessage('session-123'),
-      <String, dynamic>{
-        'type': 'attach',
-        'sessionId': 'session-123',
-      },
-    );
+    expect(client.buildAttachMessage('session-123'), <String, dynamic>{
+      'type': 'attach',
+      'sessionId': 'session-123',
+    });
   });
 
   test('builds input message for terminal input', () {
     final client = AgentSocketClient(Uri.parse('https://host:9443'));
 
-    expect(
-      client.buildInputMessage('ls'),
-      <String, dynamic>{
-        'type': 'input',
-        'input': 'ls',
-      },
-    );
-  });
-
-  test('builds screen sync message for terminal resync', () {
-    final client = AgentSocketClient(Uri.parse('https://host:9443'));
-
-    expect(
-      client.buildScreenSyncMessage(),
-      <String, dynamic>{
-        'type': 'screen_sync',
-      },
-    );
+    expect(client.buildInputMessage('ls'), <String, dynamic>{
+      'type': 'input',
+      'input': 'ls',
+    });
   });
 }
diff --git a/apps/mobile_app/test/features/terminal/terminal_screen_state_test.dart b/apps/mobile_app/test/features/terminal/terminal_screen_state_test.dart
new file mode 100644
index 0000000..539a37c
--- /dev/null
+++ b/apps/mobile_app/test/features/terminal/terminal_screen_state_test.dart
@@ -0,0 +1,89 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:term_remote_ctl/features/terminal/terminal_screen_snapshot.dart';
+import 'package:term_remote_ctl/features/terminal/terminal_screen_state.dart';
+import 'package:xterm/xterm.dart';
+
+void main() {
+  test(
+    'experiment display text trims trailing blank rows beyond the cursor',
+    () {
+      final state = TerminalScreenState.fromSnapshot(
+        const TerminalScreenSnapshot(
+          sessionId: 'session-1',
+          screenVersion: 4,
+          sourceSequence: 10,
+          rows: 24,
+          columns: 80,
+          cursorRow: 0,
+          cursorColumn: 7,
+          cursorVisible: true,
+          activeBuffer: 'primary',
+          primaryBuffer: TerminalScreenBuffer(
+            viewport: [TerminalScreenLine(index: 0, text: 'PS> git')],
+          ),
+        ),
+      );
+
+      expect(state.toDisplayText(), 'PS> git');
+    },
+  );
+
+  test(
+    'experiment display text preserves blank rows that still contain the cursor',
+    () {
+      final state = TerminalScreenState.fromSnapshot(
+        const TerminalScreenSnapshot(
+          sessionId: 'session-1',
+          screenVersion: 4,
+          sourceSequence: 10,
+          rows: 24,
+          columns: 80,
+          cursorRow: 1,
+          cursorColumn: 0,
+          cursorVisible: true,
+          activeBuffer: 'primary',
+          primaryBuffer: TerminalScreenBuffer(
+            viewport: [TerminalScreenLine(index: 0, text: 'build finished')],
+          ),
+        ),
+      );
+
+      expect(state.toDisplayText(), 'build finished\n');
+    },
+  );
+
+  test(
+    'experiment replay sequence restores the cursor to the backend screen position',
+    () {
+      final state = TerminalScreenState.fromSnapshot(
+        const TerminalScreenSnapshot(
+          sessionId: 'session-1',
+          screenVersion: 4,
+          sourceSequence: 10,
+          rows: 4,
+          columns: 12,
+          cursorRow: 2,
+          cursorColumn: 3,
+          cursorVisible: true,
+          activeBuffer: 'primary',
+          primaryBuffer: TerminalScreenBuffer(
+            viewport: [
+              TerminalScreenLine(index: 0, text: 'header'),
+              TerminalScreenLine(index: 2, text: 'pwd'),
+            ],
+          ),
+        ),
+      );
+      final terminal = Terminal(maxLines: 1000);
+
+      terminal.resize(12, 4);
+      terminal.write('stale-output');
+      terminal.write(state.toReplaySequence());
+
+      expect(terminal.buffer.getText(), contains('header'));
+      expect(terminal.buffer.getText(), contains('\n\npwd'));
+      expect(terminal.buffer.cursorY, 2);
+      expect(terminal.buffer.cursorX, 3);
+    },
+  );
+}
diff --git a/apps/mobile_app/test/features/terminal/terminal_session_coordinator_test.dart b/apps/mobile_app/test/features/terminal/terminal_session_coordinator_test.dart
index 10ea968..58e510a 100644
--- a/apps/mobile_app/test/features/terminal/terminal_session_coordinator_test.dart
+++ b/apps/mobile_app/test/features/terminal/terminal_session_coordinator_test.dart
@@ -7,8 +7,6 @@ import 'package:term_remote_ctl/features/sessions/session.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_interaction_controller.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_output_payload.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_restore_payload.dart';
-import 'package:term_remote_ctl/features/terminal/terminal_screen_patch.dart';
-import 'package:term_remote_ctl/features/terminal/terminal_screen_snapshot.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_session_coordinator.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_socket_session.dart';
 
@@ -199,10 +197,12 @@ void main() {
       await coordinator.loadOlderHistory();
 
       expect(apiClient.requestedJournalBeforeSequences, [null, 201]);
-      expect(
-        controller.historyWindow.lines,
-        ['[output] zero', '[attach]', '[output] one', '[output] two'],
-      );
+      expect(controller.historyWindow.lines, [
+        '[output] zero',
+        '[attach]',
+        '[output] one',
+        '[output] two',
+      ]);
       expect(controller.historyWindow.hasMoreAbove, isFalse);
     },
   );
@@ -584,394 +584,6 @@ void main() {
     expect(restores, hasLength(1));
     expect(restores.single.pendingInput, 't status');
   });
-
-  test('screen snapshots are forwarded before legacy restore fallback', () async {
-    final controller = TerminalInteractionController();
-    final apiClient = _FakeAgentApiClient();
-    final sessionFactory = _FakeTerminalSessionFactory();
-    final session = Session(
-      sessionId: 'abc',
-      name: 'codex-main',
-      status: 'idle',
-    );
-    final snapshots = <TerminalScreenSnapshot>[];
-    final restores = <TerminalRestorePayload>[];
-    final coordinator = TerminalSessionCoordinator(
-      controller: controller,
-      apiClient: apiClient,
-      session: session,
-      sessionFactory: sessionFactory.create,
-      onFrame: (_) {},
-      onRestore: restores.add,
-      onScreenSnapshot: snapshots.add,
-      viewportProvider: () => const TerminalViewport(columns: 80, rows: 24),
-    );
-
-    await coordinator.start();
-
-    sessionFactory.createdSessions.single.emitScreenSnapshot(
-      TerminalScreenSnapshot.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'screenVersion': 4,
-        'sourceSequence': 3,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 7,
-        'cursorVisible': true,
-        'activeBuffer': 'primary',
-        'primaryBuffer': <String, dynamic>{
-          'viewport': <Map<String, dynamic>>[
-            <String, dynamic>{'index': 0, 'text': 'PS> git'},
-          ],
-        },
-      }),
-    );
-    sessionFactory.createdSessions.single.emitRestore(
-      const TerminalRestorePayload(
-        sessionId: 'abc',
-        sequence: 4,
-        screenText: 'PS> gi',
-        pendingInput: 't status',
-      ),
-    );
-
-    expect(snapshots, hasLength(1));
-    expect(snapshots.single.toDisplayText(), 'PS> git');
-    expect(restores, hasLength(1));
-  });
-
-  test('screen patch is applied when base screen version is continuous', () async {
-    final controller = TerminalInteractionController();
-    final apiClient = _FakeAgentApiClient();
-    final sessionFactory = _FakeTerminalSessionFactory();
-    final session = Session(
-      sessionId: 'abc',
-      name: 'codex-main',
-      status: 'idle',
-    );
-    final patches = <TerminalScreenPatch>[];
-    final coordinator = TerminalSessionCoordinator(
-      controller: controller,
-      apiClient: apiClient,
-      session: session,
-      sessionFactory: sessionFactory.create,
-      onFrame: (_) {},
-      onRestore: (_) {},
-      onScreenPatch: patches.add,
-      viewportProvider: () => const TerminalViewport(columns: 80, rows: 24),
-    );
-
-    await coordinator.start();
-
-    sessionFactory.createdSessions.single.emitScreenSnapshot(
-      TerminalScreenSnapshot.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'screenVersion': 4,
-        'sourceSequence': 7,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 7,
-        'cursorVisible': true,
-        'activeBuffer': 'primary',
-        'primaryBuffer': <String, dynamic>{
-          'viewport': <Map<String, dynamic>>[
-            <String, dynamic>{'index': 0, 'text': 'PS> git'},
-          ],
-        },
-      }),
-    );
-
-    sessionFactory.createdSessions.single.emitScreenPatch(
-      TerminalScreenPatch.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'baseScreenVersion': 4,
-        'screenVersion': 5,
-        'sourceSequence': 8,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 14,
-        'cursorVisible': true,
-        'operations': <Map<String, dynamic>>[
-          <String, dynamic>{
-            'type': 'replace_lines',
-            'startRow': 0,
-            'lines': <String>['PS> git status'],
-          },
-        ],
-      }),
-    );
-
-    expect(patches, hasLength(1));
-    expect(patches.single.baseScreenVersion, 4);
-    expect(patches.single.operations.single.lines, ['PS> git status']);
-  });
-
-  test('screen patch is ignored when base screen version does not match', () async {
-    final controller = TerminalInteractionController();
-    final apiClient = _FakeAgentApiClient();
-    final sessionFactory = _FakeTerminalSessionFactory();
-    final session = Session(
-      sessionId: 'abc',
-      name: 'codex-main',
-      status: 'idle',
-    );
-    final patches = <TerminalScreenPatch>[];
-    final coordinator = TerminalSessionCoordinator(
-      controller: controller,
-      apiClient: apiClient,
-      session: session,
-      sessionFactory: sessionFactory.create,
-      onFrame: (_) {},
-      onRestore: (_) {},
-      onScreenPatch: patches.add,
-      viewportProvider: () => const TerminalViewport(columns: 80, rows: 24),
-    );
-
-    await coordinator.start();
-
-    sessionFactory.createdSessions.single.emitScreenSnapshot(
-      TerminalScreenSnapshot.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'screenVersion': 4,
-        'sourceSequence': 7,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 7,
-        'cursorVisible': true,
-        'activeBuffer': 'primary',
-        'primaryBuffer': <String, dynamic>{
-          'viewport': <Map<String, dynamic>>[
-            <String, dynamic>{'index': 0, 'text': 'PS> git'},
-          ],
-        },
-      }),
-    );
-
-    sessionFactory.createdSessions.single.emitScreenPatch(
-      TerminalScreenPatch.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'baseScreenVersion': 3,
-        'screenVersion': 5,
-        'sourceSequence': 8,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 14,
-        'cursorVisible': true,
-        'operations': <Map<String, dynamic>>[
-          <String, dynamic>{
-            'type': 'replace_lines',
-            'startRow': 0,
-            'lines': <String>['PS> git status'],
-          },
-        ],
-      }),
-    );
-
-    expect(patches, isEmpty);
-  });
-
-  test('screen patch mismatch requests a fresh screen snapshot resync', () async {
-    final controller = TerminalInteractionController();
-    final apiClient = _FakeAgentApiClient();
-    final sessionFactory = _FakeTerminalSessionFactory();
-    final session = Session(
-      sessionId: 'abc',
-      name: 'codex-main',
-      status: 'idle',
-    );
-    final patches = <TerminalScreenPatch>[];
-    final snapshots = <TerminalScreenSnapshot>[];
-    final coordinator = TerminalSessionCoordinator(
-      controller: controller,
-      apiClient: apiClient,
-      session: session,
-      sessionFactory: sessionFactory.create,
-      onFrame: (_) {},
-      onRestore: (_) {},
-      onScreenPatch: patches.add,
-      onScreenSnapshot: snapshots.add,
-      viewportProvider: () => const TerminalViewport(columns: 80, rows: 24),
-    );
-
-    await coordinator.start();
-
-    sessionFactory.createdSessions.single.emitScreenSnapshot(
-      TerminalScreenSnapshot.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'screenVersion': 4,
-        'sourceSequence': 7,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 7,
-        'cursorVisible': true,
-        'activeBuffer': 'primary',
-        'primaryBuffer': <String, dynamic>{
-          'viewport': <Map<String, dynamic>>[
-            <String, dynamic>{'index': 0, 'text': 'PS> git'},
-          ],
-        },
-      }),
-    );
-
-    sessionFactory.createdSessions.single.emitScreenPatch(
-      TerminalScreenPatch.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'baseScreenVersion': 1,
-        'screenVersion': 5,
-        'sourceSequence': 8,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 14,
-        'cursorVisible': true,
-        'operations': <Map<String, dynamic>>[
-          <String, dynamic>{
-            'type': 'replace_lines',
-            'startRow': 0,
-            'lines': <String>['PS> git status'],
-          },
-        ],
-      }),
-    );
-
-    expect(patches, isEmpty);
-    expect(sessionFactory.createdSessions.single.screenSyncRequestCount, 1);
-
-    sessionFactory.createdSessions.single.emitScreenSnapshot(
-      TerminalScreenSnapshot.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'screenVersion': 5,
-        'sourceSequence': 8,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 14,
-        'cursorVisible': true,
-        'activeBuffer': 'primary',
-        'primaryBuffer': <String, dynamic>{
-          'viewport': <Map<String, dynamic>>[
-            <String, dynamic>{'index': 0, 'text': 'PS> git status'},
-          ],
-        },
-      }),
-    );
-
-    expect(snapshots, hasLength(2));
-    expect(snapshots.last.screenVersion, 5);
-  });
-
-  test('repeated screen patch mismatches only request one resync until a snapshot arrives', () async {
-    final controller = TerminalInteractionController();
-    final apiClient = _FakeAgentApiClient();
-    final sessionFactory = _FakeTerminalSessionFactory();
-    final session = Session(
-      sessionId: 'abc',
-      name: 'codex-main',
-      status: 'idle',
-    );
-    final coordinator = TerminalSessionCoordinator(
-      controller: controller,
-      apiClient: apiClient,
-      session: session,
-      sessionFactory: sessionFactory.create,
-      onFrame: (_) {},
-      onRestore: (_) {},
-      viewportProvider: () => const TerminalViewport(columns: 80, rows: 24),
-    );
-
-    await coordinator.start();
-
-    sessionFactory.createdSessions.single.emitScreenSnapshot(
-      TerminalScreenSnapshot.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'screenVersion': 4,
-        'sourceSequence': 7,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 7,
-        'cursorVisible': true,
-        'activeBuffer': 'primary',
-        'primaryBuffer': <String, dynamic>{
-          'viewport': <Map<String, dynamic>>[
-            <String, dynamic>{'index': 0, 'text': 'PS> git'},
-          ],
-        },
-      }),
-    );
-
-    final mismatchPatch = TerminalScreenPatch.fromJson(const <String, dynamic>{
-      'sessionId': 'abc',
-      'baseScreenVersion': 1,
-      'screenVersion': 5,
-      'sourceSequence': 8,
-      'rows': 24,
-      'columns': 80,
-      'cursorRow': 0,
-      'cursorColumn': 14,
-      'cursorVisible': true,
-      'operations': <Map<String, dynamic>>[
-        <String, dynamic>{
-          'type': 'replace_lines',
-          'startRow': 0,
-          'lines': <String>['PS> git status'],
-        },
-      ],
-    });
-
-    sessionFactory.createdSessions.single.emitScreenPatch(mismatchPatch);
-    sessionFactory.createdSessions.single.emitScreenPatch(mismatchPatch);
-
-    expect(sessionFactory.createdSessions.single.screenSyncRequestCount, 1);
-
-    sessionFactory.createdSessions.single.emitScreenSnapshot(
-      TerminalScreenSnapshot.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'screenVersion': 5,
-        'sourceSequence': 8,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 14,
-        'cursorVisible': true,
-        'activeBuffer': 'primary',
-        'primaryBuffer': <String, dynamic>{
-          'viewport': <Map<String, dynamic>>[
-            <String, dynamic>{'index': 0, 'text': 'PS> git status'},
-          ],
-        },
-      }),
-    );
-
-    sessionFactory.createdSessions.single.emitScreenPatch(
-      TerminalScreenPatch.fromJson(const <String, dynamic>{
-        'sessionId': 'abc',
-        'baseScreenVersion': 3,
-        'screenVersion': 6,
-        'sourceSequence': 9,
-        'rows': 24,
-        'columns': 80,
-        'cursorRow': 0,
-        'cursorColumn': 18,
-        'cursorVisible': true,
-        'operations': <Map<String, dynamic>>[
-          <String, dynamic>{
-            'type': 'replace_lines',
-            'startRow': 0,
-            'lines': <String>['still mismatched'],
-          },
-        ],
-      }),
-    );
-
-    expect(sessionFactory.createdSessions.single.screenSyncRequestCount, 2);
-  });
 }
 
 class _FakeAgentApiClient extends AgentApiClient {
@@ -1052,7 +664,6 @@ class _FakeTerminalSocketSession extends TerminalSocketSession {
   final bool autoConnect;
   final resizeCalls = <List<int>>[];
   final sentInputs = <String>[];
-  int screenSyncRequestCount = 0;
   int disposeCount = 0;
   Completer<void>? disposeCompleter;
   Completer<void> _connectCompleter = Completer<void>();
@@ -1061,21 +672,15 @@ class _FakeTerminalSocketSession extends TerminalSocketSession {
   void Function()? _onDisconnected;
   bool _isDisconnected = false;
   void Function(TerminalRestorePayload restore)? _onRestore;
-  void Function(TerminalScreenSnapshot snapshot)? _onScreenSnapshot;
-  void Function(TerminalScreenPatch patch)? _onScreenPatch;
 
   @override
   Future<void> connect({
     required void Function(TerminalOutputPayload output) onOutput,
     required void Function(TerminalRestorePayload restore) onRestore,
-    void Function(TerminalScreenSnapshot snapshot)? onScreenSnapshot,
-    void Function(TerminalScreenPatch patch)? onScreenPatch,
     void Function()? onDisconnected,
   }) {
     _onOutput = onOutput;
     _onRestore = onRestore;
-    _onScreenSnapshot = onScreenSnapshot;
-    _onScreenPatch = onScreenPatch;
     _onDisconnected = onDisconnected;
     if (autoConnect && !_connectCompleter.isCompleted) {
       _connectCompleter.complete();
@@ -1112,19 +717,6 @@ class _FakeTerminalSocketSession extends TerminalSocketSession {
     _onRestore?.call(restore);
   }
 
-  void emitScreenSnapshot(TerminalScreenSnapshot snapshot) {
-    _onScreenSnapshot?.call(snapshot);
-  }
-
-  void emitScreenPatch(TerminalScreenPatch patch) {
-    _onScreenPatch?.call(patch);
-  }
-
-  @override
-  void requestScreenSync() {
-    screenSyncRequestCount += 1;
-  }
-
   void disconnect() {
     _isDisconnected = true;
     _onDisconnected?.call();
diff --git a/apps/mobile_app/test/features/terminal/terminal_socket_session_test.dart b/apps/mobile_app/test/features/terminal/terminal_socket_session_test.dart
index 6dcd715..aab9405 100644
--- a/apps/mobile_app/test/features/terminal/terminal_socket_session_test.dart
+++ b/apps/mobile_app/test/features/terminal/terminal_socket_session_test.dart
@@ -4,8 +4,6 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:term_remote_ctl/core/network/agent_socket_client.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_output_payload.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_restore_payload.dart';
-import 'package:term_remote_ctl/features/terminal/terminal_screen_patch.dart';
-import 'package:term_remote_ctl/features/terminal/terminal_screen_snapshot.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_socket_session.dart';
 
 void main() {
@@ -19,12 +17,11 @@ void main() {
 
     final outputs = <TerminalOutputPayload>[];
     var completed = false;
-    final connectFuture = session.connect(
-      onOutput: outputs.add,
-      onRestore: (_) {},
-    ).then((_) {
-      completed = true;
-    });
+    final connectFuture = session
+        .connect(onOutput: outputs.add, onRestore: (_) {})
+        .then((_) {
+          completed = true;
+        });
     await Future<void>.delayed(Duration.zero);
 
     expect(
@@ -50,19 +47,25 @@ void main() {
     await session.dispose();
   });
 
-  test('connect fails if the socket closes before attach acknowledgement', () async {
-    final transport = _FakeTerminalSocketTransport();
-    final session = TerminalSocketSession(
-      sessionId: 'session-123',
-      socketClient: AgentSocketClient(Uri.parse('https://host:9443')),
-      transportFactory: (_) => transport,
-    );
+  test(
+    'connect fails if the socket closes before attach acknowledgement',
+    () async {
+      final transport = _FakeTerminalSocketTransport();
+      final session = TerminalSocketSession(
+        sessionId: 'session-123',
+        socketClient: AgentSocketClient(Uri.parse('https://host:9443')),
+        transportFactory: (_) => transport,
+      );
 
-    final connectFuture = session.connect(onOutput: (_) {}, onRestore: (_) {});
-    await transport.close();
+      final connectFuture = session.connect(
+        onOutput: (_) {},
+        onRestore: (_) {},
+      );
+      await transport.close();
 
-    await expectLater(connectFuture, throwsStateError);
-  });
+      await expectLater(connectFuture, throwsStateError);
+    },
+  );
 
   test('sendInput serializes the input message', () async {
     final transport = _FakeTerminalSocketTransport();
@@ -109,29 +112,6 @@ void main() {
     await session.dispose();
   });
 
-  test('requestScreenSync serializes the screen sync message', () async {
-    final transport = _FakeTerminalSocketTransport();
-    final session = TerminalSocketSession(
-      sessionId: 'session-123',
-      socketClient: AgentSocketClient(Uri.parse('https://host:9443')),
-      transportFactory: (_) => transport,
-    );
-
-    final connectFuture = session.connect(onOutput: (_) {}, onRestore: (_) {});
-    await Future<void>.delayed(Duration.zero);
-    transport.emit('{"type":"attached","sessionId":"session-123"}');
-    await connectFuture;
-
-    session.requestScreenSync();
-
-    expect(
-      transport.sentMessages,
-      contains('{"type":"screen_sync"}'),
-    );
-
-    await session.dispose();
-  });
-
   test('connect notifies when an attached socket closes', () async {
     final transport = _FakeTerminalSocketTransport();
     final session = TerminalSocketSession(
@@ -189,11 +169,9 @@ void main() {
     );
 
     final outputs = <TerminalOutputPayload>[];
-    final snapshots = <TerminalScreenSnapshot>[];
     final restores = <TerminalRestorePayload>[];
     final connectFuture = session.connect(
       onOutput: outputs.add,
-      onScreenSnapshot: snapshots.add,
       onRestore: restores.add,
     );
     await Future<void>.delayed(Duration.zero);
@@ -201,9 +179,6 @@ void main() {
     transport.emit('{"type":"attached","sessionId":"session-123"}');
     await connectFuture;
 
-    transport.emit(
-      '{"type":"screen_snapshot","sessionId":"session-123","screenVersion":4,"sourceSequence":3,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":7,"cursorVisible":true,"activeBuffer":"primary","primaryBuffer":{"viewport":[{"index":0,"text":"PS> git"}]}}',
-    );
     transport.emit(
       '{"type":"restore","sessionId":"session-123","sequence":4,"screenText":"PS> gi","pendingInput":"t status"}',
     );
@@ -212,10 +187,6 @@ void main() {
     );
     await Future<void>.delayed(Duration.zero);
 
-    expect(snapshots, hasLength(1));
-    expect(snapshots.single.sessionId, 'session-123');
-    expect(snapshots.single.screenVersion, 4);
-    expect(snapshots.single.toDisplayText(), 'PS> git');
     expect(restores, hasLength(1));
     expect(restores.single.sessionId, 'session-123');
     expect(restores.single.sequence, 4);
@@ -249,44 +220,6 @@ void main() {
 
     expect(outputs, isEmpty);
   });
-
-  test('connect routes screen patch frames separately from output frames', () async {
-    final transport = _FakeTerminalSocketTransport();
-    final session = TerminalSocketSession(
-      sessionId: 'session-123',
-      socketClient: AgentSocketClient(Uri.parse('https://host:9443')),
-      transportFactory: (_) => transport,
-    );
-
-    final outputs = <TerminalOutputPayload>[];
-    final patches = <TerminalScreenPatch>[];
-    final connectFuture = session.connect(
-      onOutput: outputs.add,
-      onRestore: (_) {},
-      onScreenPatch: patches.add,
-    );
-    await Future<void>.delayed(Duration.zero);
-
-    transport.emit('{"type":"attached","sessionId":"session-123"}');
-    await connectFuture;
-
-    transport.emit(
-      '{"type":"screen_patch","sessionId":"session-123","baseScreenVersion":4,"screenVersion":5,"sourceSequence":8,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":8,"cursorVisible":true,"operations":[{"type":"replace_lines","startRow":0,"lines":["PS> git "]},{"type":"replace_lines","startRow":1,"lines":["status"]}]}',
-    );
-    transport.emit(
-      '{"type":"output","sessionId":"session-123","sequence":8,"chunk":"status"}',
-    );
-    await Future<void>.delayed(Duration.zero);
-
-    expect(patches, hasLength(1));
-    expect(patches.single.baseScreenVersion, 4);
-    expect(patches.single.screenVersion, 5);
-    expect(patches.single.operations, hasLength(2));
-    expect(patches.single.operations.first.startRow, 0);
-    expect(patches.single.operations.first.lines, ['PS> git ']);
-    expect(outputs, hasLength(1));
-    expect(outputs.single.chunk, 'status');
-  });
 }
 
 class _FakeTerminalSocketTransport implements TerminalSocketTransport {
diff --git a/apps/mobile_app/test/terminal_session_coordinator_diagnostics_test.dart b/apps/mobile_app/test/terminal_session_coordinator_diagnostics_test.dart
index 7719872..b873c5a 100644
--- a/apps/mobile_app/test/terminal_session_coordinator_diagnostics_test.dart
+++ b/apps/mobile_app/test/terminal_session_coordinator_diagnostics_test.dart
@@ -9,8 +9,6 @@ import 'package:term_remote_ctl/features/terminal/terminal_diagnostic_log.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_interaction_controller.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_output_payload.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_restore_payload.dart';
-import 'package:term_remote_ctl/features/terminal/terminal_screen_patch.dart';
-import 'package:term_remote_ctl/features/terminal/terminal_screen_snapshot.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_session_coordinator.dart';
 import 'package:term_remote_ctl/features/terminal/terminal_socket_session.dart';
 
@@ -120,8 +118,6 @@ class _RecordingTerminalSocketSession extends TerminalSocketSession {
   Future<void> connect({
     required void Function(TerminalOutputPayload output) onOutput,
     required void Function(TerminalRestorePayload restore) onRestore,
-    void Function(TerminalScreenSnapshot snapshot)? onScreenSnapshot,
-    void Function(TerminalScreenPatch patch)? onScreenPatch,
     void Function()? onDisconnected,
   }) async {}
 
diff --git a/apps/mobile_app/test/widget_test.dart b/apps/mobile_app/test/widget_test.dart
index 6e6d789..f92d139 100644
--- a/apps/mobile_app/test/widget_test.dart
+++ b/apps/mobile_app/test/widget_test.dart
@@ -319,144 +319,38 @@ void main() {
     expect(terminal.buffer.getText(), contains('PS> git status'));
   });
 
-  testWidgets('terminal applies backend screen snapshot as current screen', (
-    tester,
-  ) async {
-    final transportFactory = _QueuedTerminalSocketTransportFactory(
-      connectionStartupFrames: const [
-        [
-          _StartupFrame('{"type":"attached","sessionId":"session-1"}'),
-          _StartupFrame(
-            '{"type":"screen_snapshot","sessionId":"session-1","screenVersion":4,"sourceSequence":3,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":7,"cursorVisible":true,"activeBuffer":"primary","primaryBuffer":{"viewport":[{"index":0,"text":"PS> git"}]}}',
-          ),
+  testWidgets(
+    'terminal ignores backend screen snapshots by default and keeps legacy restore flow',
+    (tester) async {
+      final transportFactory = _QueuedTerminalSocketTransportFactory(
+        connectionStartupFrames: const [
+          [
+            _StartupFrame('{"type":"attached","sessionId":"session-1"}'),
+            _StartupFrame(
+              '{"type":"screen_snapshot","sessionId":"session-1","screenVersion":4,"sourceSequence":3,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":13,"cursorVisible":true,"activeBuffer":"primary","primaryBuffer":{"viewport":[{"index":0,"text":"snapshot-only"}]}}',
+            ),
+            _StartupFrame(
+              '{"type":"restore","sessionId":"session-1","sequence":4,"screenText":"restore-path","pendingInput":""}',
+            ),
+          ],
         ],
-      ],
-    );
+      );
 
-    await _pumpTerminalPage(
-      tester,
-      session: _session('session-1', 'codex-main'),
-      socketFactory: TerminalSocketSessionFactory(
-        transportFactory: transportFactory.create,
-      ),
-    );
+      await _pumpTerminalPage(
+        tester,
+        session: _session('session-1', 'codex-main'),
+        socketFactory: TerminalSocketSessionFactory(
+          transportFactory: transportFactory.create,
+        ),
+      );
 
-    final terminal = tester
-        .widget<TerminalView>(find.byType(TerminalView))
-        .terminal;
-    expect(terminal.buffer.getText(), contains('PS> git'));
-  });
-
-  testWidgets('terminal requests screen resync after patch mismatch and applies fresh snapshot', (
-    tester,
-  ) async {
-    final transportFactory = _QueuedTerminalSocketTransportFactory(
-      connectionStartupFrames: [
-        [
-          const _StartupFrame('{"type":"attached","sessionId":"session-1"}'),
-          const _StartupFrame(
-            '{"type":"screen_snapshot","sessionId":"session-1","screenVersion":4,"sourceSequence":7,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":7,"cursorVisible":true,"activeBuffer":"primary","primaryBuffer":{"viewport":[{"index":0,"text":"PS> git"}]}}',
-          ),
-          const _StartupFrame(
-            '{"type":"screen_patch","sessionId":"session-1","baseScreenVersion":1,"screenVersion":5,"sourceSequence":8,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":14,"cursorVisible":true,"operations":[{"type":"replace_lines","startRow":0,"lines":["stale patch"]}]}',
-            delay: Duration(milliseconds: 20),
-          ),
-        ],
-      ],
-      onMessageSent: (transport, message) {
-        if (message == '{"type":"screen_sync"}') {
-          transport.emit(
-            '{"type":"screen_snapshot","sessionId":"session-1","screenVersion":5,"sourceSequence":8,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":14,"cursorVisible":true,"activeBuffer":"primary","primaryBuffer":{"viewport":[{"index":0,"text":"PS> git status"}]}}',
-          );
-        }
-      },
-    );
-
-    await _pumpTerminalPage(
-      tester,
-      session: _session('session-1', 'codex-main'),
-      socketFactory: TerminalSocketSessionFactory(
-        transportFactory: transportFactory.create,
-      ),
-    );
-
-    await tester.pump(const Duration(milliseconds: 40));
-
-    expect(
-      transportFactory.createdTransports.single.sentMessages,
-      contains('{"type":"screen_sync"}'),
-    );
-
-    final terminal = tester
-        .widget<TerminalView>(find.byType(TerminalView))
-        .terminal;
-    expect(terminal.buffer.getText(), contains('PS> git status'));
-    expect(terminal.buffer.getText(), isNot(contains('stale patch')));
-  });
-
-  testWidgets('terminal renders alternate buffer when backend marks it active', (
-    tester,
-  ) async {
-    final transportFactory = _QueuedTerminalSocketTransportFactory(
-      connectionStartupFrames: const [
-        [
-          _StartupFrame('{"type":"attached","sessionId":"session-1"}'),
-          _StartupFrame(
-            '{"type":"screen_snapshot","sessionId":"session-1","screenVersion":4,"sourceSequence":3,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":3,"cursorVisible":true,"activeBuffer":"alternate","primaryBuffer":{"viewport":[{"index":0,"text":"primary shell"}]},"alternateBuffer":{"viewport":[{"index":0,"text":"alt ui"}]}}',
-          ),
-        ],
-      ],
-    );
-
-    await _pumpTerminalPage(
-      tester,
-      session: _session('session-1', 'codex-main'),
-      socketFactory: TerminalSocketSessionFactory(
-        transportFactory: transportFactory.create,
-      ),
-    );
-
-    final terminal = tester
-        .widget<TerminalView>(find.byType(TerminalView))
-        .terminal;
-    expect(terminal.buffer.getText(), contains('alt ui'));
-    expect(terminal.buffer.getText(), isNot(contains('primary shell')));
-  });
-
-  testWidgets('terminal switches back to primary when screen patch changes active buffer', (
-    tester,
-  ) async {
-    final transportFactory = _QueuedTerminalSocketTransportFactory(
-      connectionStartupFrames: const [
-        [
-          _StartupFrame('{"type":"attached","sessionId":"session-1"}'),
-          _StartupFrame(
-            '{"type":"screen_snapshot","sessionId":"session-1","screenVersion":4,"sourceSequence":3,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":3,"cursorVisible":true,"activeBuffer":"alternate","primaryBuffer":{"viewport":[{"index":0,"text":"primary shell"}]},"alternateBuffer":{"viewport":[{"index":0,"text":"alt ui"}]}}',
-          ),
-          _StartupFrame(
-            '{"type":"screen_patch","sessionId":"session-1","baseScreenVersion":4,"screenVersion":5,"sourceSequence":4,"rows":24,"columns":80,"cursorRow":0,"cursorColumn":13,"cursorVisible":true,"activeBuffer":"primary","operations":[{"type":"replace_lines","startRow":0,"lines":["primary shell"]}]}',
-            delay: Duration(milliseconds: 20),
-          ),
-        ],
-      ],
-    );
-
-    await _pumpTerminalPage(
-      tester,
-      session: _session('session-1', 'codex-main'),
-      socketFactory: TerminalSocketSessionFactory(
-        transportFactory: transportFactory.create,
-      ),
-    );
-
-    await tester.pump(const Duration(milliseconds: 40));
-
-    final terminal = tester
-        .widget<TerminalView>(find.byType(TerminalView))
-        .terminal;
-    expect(terminal.buffer.getText(), contains('primary shell'));
-    expect(terminal.buffer.getText(), isNot(contains('alt ui')));
-  });
+      final terminal = tester
+          .widget<TerminalView>(find.byType(TerminalView))
+          .terminal;
+      expect(terminal.buffer.getText(), contains('restore-path'));
+      expect(terminal.buffer.getText(), isNot(contains('snapshot-only')));
+    },
+  );
 
   testWidgets(
     'terminal page keeps the command deck above the bottom safe area',
@@ -1051,12 +945,12 @@ void main() {
 
       await _openProjectTerminal(tester);
 
-      expect(find.text('Scrollback | 2 lines'), findsNothing);
+      expect(find.text('Scrollback'), findsNothing);
 
-      await tester.tap(find.textContaining('Live |'));
+      await tester.tap(find.text('Live'));
       await tester.pumpAndSettle();
 
-      expect(find.text('Scrollback | 2 lines'), findsOneWidget);
+      expect(find.text('Scrollback'), findsOneWidget);
       expect(find.text('Load older lines'), findsOneWidget);
 
       await tester.ensureVisible(find.text('Load older lines'));
@@ -1202,7 +1096,7 @@ void main() {
       expect(terminal.buffer.cursorX, 3);
       expect(terminal.buffer.getText(), contains('one\ntwo'));
 
-      await tester.tap(find.textContaining('Live |'));
+      await tester.tap(find.text('Live'));
       await tester.pumpAndSettle();
       await tester.ensureVisible(find.text('Load older lines'));
       await tester.tap(find.text('Load older lines'));
diff --git a/apps/windows_agent/src/TermRemoteCtl.Agent/Configuration/AgentOptions.cs b/apps/windows_agent/src/TermRemoteCtl.Agent/Configuration/AgentOptions.cs
index 644fa0d..0ad789c 100644
--- a/apps/windows_agent/src/TermRemoteCtl.Agent/Configuration/AgentOptions.cs
+++ b/apps/windows_agent/src/TermRemoteCtl.Agent/Configuration/AgentOptions.cs
@@ -18,6 +18,8 @@ public sealed class AgentOptions
 
     public int SessionJournalRetentionDays { get; set; } = 7;
 
+    public bool EnableBackendScreenProtocol { get; set; }
+
     public bool HasHttpsEndpoint => HttpsPort > 0;
 
     public bool HasHttpEndpoint => HttpPort > 0;
diff --git a/apps/windows_agent/src/TermRemoteCtl.Agent/Configuration/AgentOptionsServiceCollectionExtensions.cs b/apps/windows_agent/src/TermRemoteCtl.Agent/Configuration/AgentOptionsServiceCollectionExtensions.cs
index 2e773b1..43fb133 100644
--- a/apps/windows_agent/src/TermRemoteCtl.Agent/Configuration/AgentOptionsServiceCollectionExtensions.cs
+++ b/apps/windows_agent/src/TermRemoteCtl.Agent/Configuration/AgentOptionsServiceCollectionExtensions.cs
@@ -21,6 +21,7 @@ public static class AgentOptionsServiceCollectionExtensions
                 options.HttpPort = effectiveOptions.HttpPort;
                 options.WebSocketFrameFlushMilliseconds = effectiveOptions.WebSocketFrameFlushMilliseconds;
                 options.RingBufferLineLimit = effectiveOptions.RingBufferLineLimit;
+                options.EnableBackendScreenProtocol = effectiveOptions.EnableBackendScreenProtocol;
             })
             .ValidateOnStart();
 
diff --git a/apps/windows_agent/src/TermRemoteCtl.Agent/Realtime/TerminalWebSocketHandler.cs b/apps/windows_agent/src/TermRemoteCtl.Agent/Realtime/TerminalWebSocketHandler.cs
index b94f24e..36e1e32 100644
--- a/apps/windows_agent/src/TermRemoteCtl.Agent/Realtime/TerminalWebSocketHandler.cs
+++ b/apps/windows_agent/src/TermRemoteCtl.Agent/Realtime/TerminalWebSocketHandler.cs
@@ -1,11 +1,8 @@
 using System.Net.WebSockets;
 using System.Text;
 using System.Text.Json;
-using Microsoft.Extensions.Options;
 using TermRemoteCtl.Agent.Sessions;
 using TermRemoteCtl.Agent.Terminal;
-using TermRemoteCtl.Agent.Configuration;
-using TermRemoteCtl.Agent.Terminal.Screen;
 
 namespace TermRemoteCtl.Agent.Realtime;
 
@@ -60,58 +57,23 @@ public static class TerminalWebSocketHandler
         }
 
         using var sendGate = new SemaphoreSlim(1, 1);
-        var screenStateGate = new object();
-        var lastSentScreenSnapshot = registry.GetScreenSnapshot(sessionId);
-        async Task SendScreenSnapshotAsync(CancellationToken cancellationToken)
-        {
-            TerminalScreenSnapshot snapshot;
-            lock (screenStateGate)
-            {
-                snapshot = registry.GetScreenSnapshot(sessionId);
-                lastSentScreenSnapshot = snapshot;
-            }
-
-            await SendJsonAsync(
-                socket,
-                new TerminalScreenSnapshotResponse(
-                    snapshot.SessionId,
-                    snapshot.ScreenVersion,
-                    snapshot.SourceSequence,
-                    snapshot.Rows,
-                    snapshot.Columns,
-                    snapshot.CursorRow,
-                    snapshot.CursorColumn,
-                    snapshot.CursorVisible,
-                    snapshot.ActiveBuffer,
-                    ToBufferResponse(snapshot.PrimaryBuffer),
-                    snapshot.AlternateBuffer is null ? null : ToBufferResponse(snapshot.AlternateBuffer)),
-                sendGate,
-                cancellationToken).ConfigureAwait(false);
-        }
-
         void HandleOutput(object? sender, TerminalOutputEventArgs args)
         {
             if (string.Equals(args.SessionId, sessionId, StringComparison.Ordinal))
             {
-                TerminalScreenPatch? screenPatch = null;
-                lock (screenStateGate)
-                {
-                    var currentSnapshot = registry.GetScreenSnapshot(sessionId);
-                    screenPatch = TerminalScreenPatch.Create(lastSentScreenSnapshot, currentSnapshot);
-                    lastSentScreenSnapshot = currentSnapshot;
-                }
-
-                _ = SendOutputAndPatchAsync(socket, args, screenPatch, sendGate, context.RequestAborted);
+                _ = SendJsonAsync(
+                    socket,
+                    new TerminalOutputResponse(args.SessionId, args.Sequence, args.Chunk),
+                    sendGate,
+                    context.RequestAborted);
             }
         }
 
         try
         {
             await registry.RecordAttachAsync(sessionId, context.RequestAborted).ConfigureAwait(false);
-            var screenSnapshot = lastSentScreenSnapshot;
             var restore = registry.GetRestoreSnapshot(sessionId);
             await SendJsonAsync(socket, new TerminalAttachResponse(sessionId), sendGate, context.RequestAborted).ConfigureAwait(false);
-            await SendScreenSnapshotAsync(context.RequestAborted).ConfigureAwait(false);
             await SendJsonAsync(
                 socket,
                 new TerminalRestoreResponse(
@@ -119,12 +81,12 @@ public static class TerminalWebSocketHandler
                     restore.Sequence,
                     restore.ScreenText,
                     restore.PendingInput,
-                restore.CursorRow,
-                restore.CursorColumn),
+                    restore.CursorRow,
+                    restore.CursorColumn),
                 sendGate,
                 context.RequestAborted).ConfigureAwait(false);
             host.OutputReceived += HandleOutput;
-            await ReceiveLoopAsync(context, socket, host, registry, diagnostics, sessionId, SendScreenSnapshotAsync).ConfigureAwait(false);
+            await ReceiveLoopAsync(context, socket, host, registry, diagnostics, sessionId).ConfigureAwait(false);
         }
         finally
         {
@@ -145,8 +107,7 @@ public static class TerminalWebSocketHandler
         ISessionHost host,
         SessionRegistry registry,
         ITerminalDiagnosticsSink diagnostics,
-        string sessionId,
-        Func<CancellationToken, Task> sendScreenSnapshotAsync)
+        string sessionId)
     {
         var buffer = new byte[4096];
 
@@ -178,8 +139,7 @@ public static class TerminalWebSocketHandler
                 host,
                 diagnostics,
                 sessionId,
-                context.RequestAborted,
-                sendScreenSnapshotAsync).ConfigureAwait(false);
+                context.RequestAborted).ConfigureAwait(false);
         }
     }
 
@@ -189,8 +149,7 @@ public static class TerminalWebSocketHandler
         ISessionHost host,
         ITerminalDiagnosticsSink diagnostics,
         string sessionId,
-        CancellationToken cancellationToken,
-        Func<CancellationToken, Task> sendScreenSnapshotAsync)
+        CancellationToken cancellationToken)
     {
         TerminalClientMessage? message;
 
@@ -205,8 +164,7 @@ public static class TerminalWebSocketHandler
 
         if (message is null ||
             !string.Equals(message.Type, "input", StringComparison.OrdinalIgnoreCase) &&
-            !string.Equals(message.Type, "resize", StringComparison.OrdinalIgnoreCase) &&
-            !string.Equals(message.Type, "screen_sync", StringComparison.OrdinalIgnoreCase))
+            !string.Equals(message.Type, "resize", StringComparison.OrdinalIgnoreCase))
         {
             if (message is not null && string.Equals(message.Type, "attach", StringComparison.OrdinalIgnoreCase))
             {
@@ -228,12 +186,6 @@ public static class TerminalWebSocketHandler
             return;
         }
 
-        if (string.Equals(message.Type, "screen_sync", StringComparison.OrdinalIgnoreCase))
-        {
-            await sendScreenSnapshotAsync(cancellationToken).ConfigureAwait(false);
-            return;
-        }
-
         if (message.Columns is > 0 && message.Rows is > 0)
         {
             await registry.RecordResizeAsync(
@@ -283,76 +235,8 @@ public static class TerminalWebSocketHandler
         }
     }
 
-    private static async Task SendOutputAndPatchAsync(
-        WebSocket socket,
-        TerminalOutputEventArgs args,
-        TerminalScreenPatch? screenPatch,
-        SemaphoreSlim sendGate,
-        CancellationToken cancellationToken)
-    {
-        await SendJsonAsync(
-            socket,
-            new TerminalOutputResponse(args.SessionId, args.Sequence, args.Chunk),
-            sendGate,
-            cancellationToken).ConfigureAwait(false);
-        if (screenPatch is not null)
-        {
-            await SendJsonAsync(
-                socket,
-                ToScreenPatchResponse(screenPatch),
-                sendGate,
-                cancellationToken).ConfigureAwait(false);
-        }
-    }
-
-    private static TerminalScreenBufferResponse ToBufferResponse(TerminalScreenBufferSnapshot buffer)
-    {
-        return new TerminalScreenBufferResponse(
-            buffer.Viewport.Select(line => new TerminalScreenLineResponse(line.Index, line.Text)).ToArray());
-    }
-
-    private static TerminalScreenPatchResponse ToScreenPatchResponse(TerminalScreenPatch patch)
-    {
-        return new TerminalScreenPatchResponse(
-            patch.SessionId,
-            patch.BaseScreenVersion,
-            patch.ScreenVersion,
-            patch.SourceSequence,
-            patch.Rows,
-            patch.Columns,
-            patch.CursorRow,
-            patch.CursorColumn,
-            patch.CursorVisible,
-            patch.ActiveBuffer,
-            patch.Operations.Select(operation => new TerminalScreenPatchOperationResponse(
-                operation.Type,
-                operation.StartRow,
-                operation.Lines.ToArray())).ToArray());
-    }
-
     private sealed record TerminalAttachResponse(string SessionId, string Type = "attached");
 
-    private sealed record TerminalScreenSnapshotResponse(
-        string SessionId,
-        long ScreenVersion,
-        long SourceSequence,
-        int Rows,
-        int Columns,
-        int CursorRow,
-        int CursorColumn,
-        bool CursorVisible,
-        string ActiveBuffer,
-        TerminalScreenBufferResponse PrimaryBuffer,
-        TerminalScreenBufferResponse? AlternateBuffer,
-        string Type = "screen_snapshot");
-
-    private sealed record TerminalScreenBufferResponse(
-        IReadOnlyList<TerminalScreenLineResponse> Viewport);
-
-    private sealed record TerminalScreenLineResponse(
-        int Index,
-        string Text);
-
     private sealed record TerminalRestoreResponse(
         string SessionId,
         long Sequence,
@@ -368,25 +252,6 @@ public static class TerminalWebSocketHandler
         string Chunk,
         string Type = "output");
 
-    private sealed record TerminalScreenPatchResponse(
-        string SessionId,
-        long BaseScreenVersion,
-        long ScreenVersion,
-        long SourceSequence,
-        int Rows,
-        int Columns,
-        int CursorRow,
-        int CursorColumn,
-        bool CursorVisible,
-        string ActiveBuffer,
-        IReadOnlyList<TerminalScreenPatchOperationResponse> Operations,
-        string Type = "screen_patch");
-
-    private sealed record TerminalScreenPatchOperationResponse(
-        string Type,
-        int StartRow,
-        IReadOnlyList<string> Lines);
-
     private sealed record TerminalClientMessage(
         string Type,
         string? SessionId,
diff --git a/apps/windows_agent/src/TermRemoteCtl.Agent/Sessions/SessionRegistry.cs b/apps/windows_agent/src/TermRemoteCtl.Agent/Sessions/SessionRegistry.cs
index 92e22fe..ea5f1a3 100644
--- a/apps/windows_agent/src/TermRemoteCtl.Agent/Sessions/SessionRegistry.cs
+++ b/apps/windows_agent/src/TermRemoteCtl.Agent/Sessions/SessionRegistry.cs
@@ -9,6 +9,8 @@ namespace TermRemoteCtl.Agent.Sessions;
 public sealed class SessionRegistry
 {
     private const int ReplayCharacterLimit = 262_144;
+    private const string ScreenProtocolDisabledMessage =
+        "Backend screen protocol is disabled on the mainline product path.";
     private readonly ConcurrentDictionary<string, SessionRecord> _records = new();
     private readonly ConcurrentDictionary<string, TerminalRingBuffer> _historyBySession = new();
     private readonly ConcurrentDictionary<string, TerminalReplayBuffer> _replayBySession = new();
@@ -18,6 +20,7 @@ public sealed class SessionRegistry
     private readonly SessionHistoryStore _historyStore;
     private readonly SessionIoJournalStore _journalStore;
     private readonly int _ringBufferLineLimit;
+    private readonly bool _enableBackendScreenProtocol;
 
     public SessionRegistry(
         SessionHistoryStore historyStore,
@@ -27,6 +30,7 @@ public sealed class SessionRegistry
         _historyStore = historyStore;
         _journalStore = journalStore;
         _ringBufferLineLimit = options.Value.RingBufferLineLimit;
+        _enableBackendScreenProtocol = options.Value.EnableBackendScreenProtocol;
     }
 
     public SessionRecord Create(
@@ -50,7 +54,10 @@ public sealed class SessionRegistry
         _historyBySession[record.SessionId] = new TerminalRingBuffer(_ringBufferLineLimit);
         _replayBySession[record.SessionId] = new TerminalReplayBuffer(ReplayCharacterLimit);
         _pendingInputEchoBySession[record.SessionId] = new PendingInputEchoTracker();
-        _screenBySession[record.SessionId] = new TerminalScreenEngine();
+        if (_enableBackendScreenProtocol)
+        {
+            _screenBySession[record.SessionId] = new TerminalScreenEngine();
+        }
         _sequenceBySession[record.SessionId] = 0;
         return record;
     }
@@ -123,7 +130,6 @@ public sealed class SessionRegistry
             sessionId,
             _ => new PendingInputEchoTracker());
         pendingInputEcho.ObserveOutput(chunk);
-        var screen = _screenBySession.GetOrAdd(sessionId, _ => new TerminalScreenEngine());
         var updatedAtUtc = DateTimeOffset.UtcNow;
         var ioEvent = new SessionIoEvent(
             sessionId,
@@ -131,7 +137,11 @@ public sealed class SessionRegistry
             "output",
             chunk,
             updatedAtUtc);
-        screen.ApplyOutput(chunk, ioEvent.Sequence);
+        if (_enableBackendScreenProtocol)
+        {
+            var screen = _screenBySession.GetOrAdd(sessionId, _ => new TerminalScreenEngine());
+            screen.ApplyOutput(chunk, ioEvent.Sequence);
+        }
         _records[sessionId] = record with { UpdatedAtUtc = updatedAtUtc };
         await _historyStore.AppendAsync(sessionId, chunk, cancellationToken).ConfigureAwait(false);
         await _journalStore.AppendAsync(ioEvent, cancellationToken).ConfigureAwait(false);
@@ -189,8 +199,11 @@ public sealed class SessionRegistry
             "resize",
             $"{columns}x{rows}",
             updatedAtUtc);
-        var screen = _screenBySession.GetOrAdd(sessionId, _ => new TerminalScreenEngine());
-        screen.Resize(columns, rows);
+        if (_enableBackendScreenProtocol)
+        {
+            var screen = _screenBySession.GetOrAdd(sessionId, _ => new TerminalScreenEngine());
+            screen.Resize(columns, rows);
+        }
         _records[sessionId] = record with { UpdatedAtUtc = updatedAtUtc };
         await _journalStore.AppendAsync(ioEvent, cancellationToken).ConfigureAwait(false);
         return ioEvent;
@@ -303,6 +316,11 @@ public sealed class SessionRegistry
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(sessionId);
 
+        if (!_enableBackendScreenProtocol)
+        {
+            throw new InvalidOperationException(ScreenProtocolDisabledMessage);
+        }
+
         if (!_records.ContainsKey(sessionId))
         {
             throw new KeyNotFoundException($"Session '{sessionId}' was not found.");
diff --git a/apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenEngine.cs b/apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenEngine.cs
index 5448648..b785b30 100644
--- a/apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenEngine.cs
+++ b/apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenEngine.cs
@@ -211,7 +211,17 @@ public sealed class TerminalScreenEngine
 
     private bool TryApplyEscape(string chunk, ref int index)
     {
-        if (index + 1 >= chunk.Length || chunk[index + 1] != '[')
+        if (index + 1 >= chunk.Length)
+        {
+            return false;
+        }
+
+        if (chunk[index + 1] == ']')
+        {
+            return TryConsumeOperatingSystemCommand(chunk, ref index);
+        }
+
+        if (chunk[index + 1] != '[')
         {
             return false;
         }
@@ -235,6 +245,33 @@ public sealed class TerminalScreenEngine
         return false;
     }
 
+    private static bool TryConsumeOperatingSystemCommand(string chunk, ref int index)
+    {
+        var cursor = index + 2;
+        while (cursor < chunk.Length)
+        {
+            var current = chunk[cursor];
+            if (current == '\u0007')
+            {
+                index = cursor;
+                return true;
+            }
+
+            if (current == '\u001b' &&
+                cursor + 1 < chunk.Length &&
+                chunk[cursor + 1] == '\\')
+            {
+                index = cursor + 1;
+                return true;
+            }
+
+            cursor += 1;
+        }
+
+        index = chunk.Length - 1;
+        return true;
+    }
+
     private bool ApplyCsi(string parameterText, char command)
     {
         switch (command)
diff --git a/apps/windows_agent/src/TermRemoteCtl.Agent/appsettings.json b/apps/windows_agent/src/TermRemoteCtl.Agent/appsettings.json
index 44f0042..5f9baa0 100644
--- a/apps/windows_agent/src/TermRemoteCtl.Agent/appsettings.json
+++ b/apps/windows_agent/src/TermRemoteCtl.Agent/appsettings.json
@@ -5,6 +5,7 @@
     "HttpsPort": 0,
     "HttpPort": 5067,
     "WebSocketFrameFlushMilliseconds": 33,
-    "RingBufferLineLimit": 4000
+    "RingBufferLineLimit": 4000,
+    "EnableBackendScreenProtocol": false
   }
 }
diff --git a/apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalWebSocketHandlerTests.cs b/apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalWebSocketHandlerTests.cs
index d542d0a..e0318e9 100644
--- a/apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalWebSocketHandlerTests.cs
+++ b/apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalWebSocketHandlerTests.cs
@@ -15,6 +15,7 @@ namespace TermRemoteCtl.Agent.IntegrationTests.Realtime;
 public sealed class TerminalWebSocketHandlerTests
 {
     [Fact]
+    [Trait("Track", "Mainline")]
     public async Task Attach_Streams_Output_And_Forwards_Input()
     {
         await using var fixture = new TerminalApiFixture();
@@ -35,18 +36,6 @@ public sealed class TerminalWebSocketHandlerTests
         Assert.Equal("attached", attachedPayload!.Type);
         Assert.Equal(session.SessionId, attachedPayload.SessionId);
 
-        var screenSnapshotFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var screenSnapshotPayload = JsonSerializer.Deserialize<TerminalScreenSnapshotResponse>(
-            screenSnapshotFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-
-        Assert.NotNull(screenSnapshotPayload);
-        Assert.Equal("screen_snapshot", screenSnapshotPayload!.Type);
-        Assert.Equal(session.SessionId, screenSnapshotPayload.SessionId);
-        Assert.Equal(24, screenSnapshotPayload.Rows);
-        Assert.Equal(80, screenSnapshotPayload.Columns);
-        Assert.Equal("primary", screenSnapshotPayload.ActiveBuffer);
-
         var restoreFrame = await ReceiveTextAsync(socket, CancellationToken.None);
         var restorePayload = JsonSerializer.Deserialize<TerminalRestoreResponse>(
             restoreFrame,
@@ -69,21 +58,6 @@ public sealed class TerminalWebSocketHandlerTests
         Assert.Equal(2L, firstOutputPayload.Sequence);
         Assert.Equal("abc", firstOutputPayload.Chunk);
 
-        var firstPatchFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var firstPatchPayload = JsonSerializer.Deserialize<TerminalScreenPatchResponse>(
-            firstPatchFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-        Assert.NotNull(firstPatchPayload);
-        Assert.Equal("screen_patch", firstPatchPayload!.Type);
-        Assert.Equal(session.SessionId, firstPatchPayload.SessionId);
-        Assert.Equal(0L, firstPatchPayload.BaseScreenVersion);
-        Assert.Equal(1L, firstPatchPayload.ScreenVersion);
-        Assert.Equal(2L, firstPatchPayload.SourceSequence);
-        Assert.Single(firstPatchPayload.Operations);
-        Assert.Equal("replace_lines", firstPatchPayload.Operations[0].Type);
-        Assert.Equal(0, firstPatchPayload.Operations[0].StartRow);
-        Assert.Equal(["abc"], firstPatchPayload.Operations[0].Lines);
-
         var secondOutputFrame = await ReceiveTextAsync(socket, CancellationToken.None);
         var secondOutputPayload = JsonSerializer.Deserialize<TerminalOutputResponse>(
             secondOutputFrame,
@@ -93,18 +67,6 @@ public sealed class TerminalWebSocketHandlerTests
         Assert.Equal(3L, secondOutputPayload.Sequence);
         Assert.Equal("def", secondOutputPayload.Chunk);
 
-        var secondPatchFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var secondPatchPayload = JsonSerializer.Deserialize<TerminalScreenPatchResponse>(
-            secondPatchFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-        Assert.NotNull(secondPatchPayload);
-        Assert.Equal("screen_patch", secondPatchPayload!.Type);
-        Assert.Equal(1L, secondPatchPayload.BaseScreenVersion);
-        Assert.Equal(2L, secondPatchPayload.ScreenVersion);
-        Assert.Equal(3L, secondPatchPayload.SourceSequence);
-        Assert.Single(secondPatchPayload.Operations);
-        Assert.Equal(["abcdef"], secondPatchPayload.Operations[0].Lines);
-
         var inputMessage = JsonSerializer.Serialize(new { type = "input", input = "dir" });
         await socket.SendAsync(Encoding.UTF8.GetBytes(inputMessage), WebSocketMessageType.Text, true, CancellationToken.None);
 
@@ -115,6 +77,7 @@ public sealed class TerminalWebSocketHandlerTests
     }
 
     [Fact]
+    [Trait("Track", "Mainline")]
     public async Task Attach_Replays_Recent_Output_For_Existing_Session()
     {
         await using var fixture = new TerminalApiFixture();
@@ -135,19 +98,6 @@ public sealed class TerminalWebSocketHandlerTests
         Assert.NotNull(attachedPayload);
         Assert.Equal("attached", attachedPayload!.Type);
 
-        var screenSnapshotFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var screenSnapshotPayload = JsonSerializer.Deserialize<TerminalScreenSnapshotResponse>(
-            screenSnapshotFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-
-        Assert.NotNull(screenSnapshotPayload);
-        Assert.Equal("screen_snapshot", screenSnapshotPayload!.Type);
-        Assert.StartsWith(
-            "prompt> dir",
-            screenSnapshotPayload.PrimaryBuffer.Viewport[0].Text,
-            StringComparison.Ordinal);
-        Assert.Equal(1L, screenSnapshotPayload.SourceSequence);
-
         var restoreFrame = await ReceiveTextAsync(socket, CancellationToken.None);
         var restorePayload = JsonSerializer.Deserialize<TerminalRestoreResponse>(
             restoreFrame,
@@ -161,6 +111,7 @@ public sealed class TerminalWebSocketHandlerTests
     }
 
     [Fact]
+    [Trait("Track", "Mainline")]
     public async Task Attach_Does_Not_Duplicate_Output_Produced_During_Replay_Boundary()
     {
         await using var fixture = new TerminalApiFixture();
@@ -182,18 +133,6 @@ public sealed class TerminalWebSocketHandlerTests
         Assert.NotNull(attachedPayload);
         Assert.Equal("attached", attachedPayload!.Type);
 
-        var screenSnapshotFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var screenSnapshotPayload = JsonSerializer.Deserialize<TerminalScreenSnapshotResponse>(
-            screenSnapshotFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-
-        Assert.NotNull(screenSnapshotPayload);
-        Assert.Equal("screen_snapshot", screenSnapshotPayload!.Type);
-        Assert.StartsWith(
-            "prompt> dir",
-            screenSnapshotPayload.PrimaryBuffer.Viewport[0].Text,
-            StringComparison.Ordinal);
-
         var restoreFrame = await ReceiveTextAsync(socket, CancellationToken.None);
         var restorePayload = JsonSerializer.Deserialize<TerminalRestoreResponse>(
             restoreFrame,
@@ -213,20 +152,11 @@ public sealed class TerminalWebSocketHandlerTests
         Assert.Equal(3L, livePayload.Sequence);
         Assert.Equal("next> ", livePayload.Chunk);
 
-        var patchFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var patchPayload = JsonSerializer.Deserialize<TerminalScreenPatchResponse>(
-            patchFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-        Assert.NotNull(patchPayload);
-        Assert.Equal("screen_patch", patchPayload!.Type);
-        Assert.Equal(1L, patchPayload.BaseScreenVersion);
-        Assert.Equal(2L, patchPayload.ScreenVersion);
-        Assert.Equal(3L, patchPayload.SourceSequence);
-
         await AssertNoAdditionalTextFrameAsync(socket, TimeSpan.FromMilliseconds(200));
     }
 
     [Fact]
+    [Trait("Track", "Mainline")]
     public async Task Reattach_Replays_Visible_User_Input_When_No_Output_Echo_Has_Arrived_Yet()
     {
         await using var fixture = new TerminalApiFixture();
@@ -250,7 +180,6 @@ public sealed class TerminalWebSocketHandlerTests
             new Uri($"ws://localhost/ws/terminal?sessionId={session.SessionId}"),
             CancellationToken.None);
 
-        _ = await ReceiveTextAsync(replaySocket, CancellationToken.None);
         _ = await ReceiveTextAsync(replaySocket, CancellationToken.None);
         var restoreFrame = await ReceiveTextAsync(replaySocket, CancellationToken.None);
         var restorePayload = JsonSerializer.Deserialize<TerminalRestoreResponse>(
@@ -264,6 +193,7 @@ public sealed class TerminalWebSocketHandlerTests
     }
 
     [Fact]
+    [Trait("Track", "Mainline")]
     public async Task Reattach_Returns_Restore_Payload_With_Pending_Input()
     {
         await using var fixture = new TerminalApiFixture();
@@ -277,7 +207,6 @@ public sealed class TerminalWebSocketHandlerTests
             new Uri($"ws://localhost/ws/terminal?sessionId={session.SessionId}"),
             CancellationToken.None);
 
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
         _ = await ReceiveTextAsync(socket, CancellationToken.None);
         var restoreFrame = await ReceiveTextAsync(socket, CancellationToken.None);
 
@@ -286,144 +215,6 @@ public sealed class TerminalWebSocketHandlerTests
         Assert.Contains("\"sequence\":2", restoreFrame);
     }
 
-    [Fact]
-    public async Task Live_Output_Also_Streams_Authoritative_Screen_Patch()
-    {
-        await using var fixture = new TerminalApiFixture();
-        var registry = fixture.Services.GetRequiredService<SessionRegistry>();
-        fixture.TerminalHost.Registry = registry;
-        var session = registry.Create("Shell", DateTimeOffset.UtcNow);
-
-        using WebSocket socket = await fixture.Server.CreateWebSocketClient().ConnectAsync(
-            new Uri($"ws://localhost/ws/terminal?sessionId={session.SessionId}"),
-            CancellationToken.None);
-
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-
-        fixture.TerminalHost.EmitOutput(session.SessionId, "prompt> ");
-
-        var outputFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var outputPayload = JsonSerializer.Deserialize<TerminalOutputResponse>(
-            outputFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-        Assert.NotNull(outputPayload);
-        Assert.Equal("prompt> ", outputPayload!.Chunk);
-
-        var patchFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var patchPayload = JsonSerializer.Deserialize<TerminalScreenPatchResponse>(
-            patchFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-
-        Assert.NotNull(patchPayload);
-        Assert.Equal("screen_patch", patchPayload!.Type);
-        Assert.Equal(session.SessionId, patchPayload.SessionId);
-        Assert.Equal(0L, patchPayload.BaseScreenVersion);
-        Assert.Equal(1L, patchPayload.ScreenVersion);
-        Assert.Equal(2L, patchPayload.SourceSequence);
-        Assert.Single(patchPayload.Operations);
-        Assert.Equal("replace_lines", patchPayload.Operations[0].Type);
-        Assert.Equal(0, patchPayload.Operations[0].StartRow);
-        Assert.Equal(["prompt> "], patchPayload.Operations[0].Lines);
-    }
-
-    [Fact]
-    public async Task ScreenSync_Request_Returns_Fresh_Screen_Snapshot()
-    {
-        await using var fixture = new TerminalApiFixture();
-        var registry = fixture.Services.GetRequiredService<SessionRegistry>();
-        fixture.TerminalHost.Registry = registry;
-        var session = registry.Create("Shell", DateTimeOffset.UtcNow);
-
-        using WebSocket socket = await fixture.Server.CreateWebSocketClient().ConnectAsync(
-            new Uri($"ws://localhost/ws/terminal?sessionId={session.SessionId}"),
-            CancellationToken.None);
-
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-
-        fixture.TerminalHost.EmitOutput(session.SessionId, "prompt> ");
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-
-        var syncMessage = JsonSerializer.Serialize(new { type = "screen_sync" });
-        await socket.SendAsync(Encoding.UTF8.GetBytes(syncMessage), WebSocketMessageType.Text, true, CancellationToken.None);
-
-        var snapshotFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var snapshotPayload = JsonSerializer.Deserialize<TerminalScreenSnapshotResponse>(
-            snapshotFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-
-        Assert.NotNull(snapshotPayload);
-        Assert.Equal("screen_snapshot", snapshotPayload!.Type);
-        Assert.Equal(session.SessionId, snapshotPayload.SessionId);
-        Assert.Equal(1L, snapshotPayload.ScreenVersion);
-        Assert.Equal(2L, snapshotPayload.SourceSequence);
-        Assert.Equal("prompt> ", snapshotPayload.PrimaryBuffer.Viewport[0].Text.TrimEnd() + " ");
-    }
-
-    [Fact]
-    public async Task Attach_Returns_Alternate_Buffer_When_Alternate_Screen_Is_Active()
-    {
-        await using var fixture = new TerminalApiFixture();
-        var registry = fixture.Services.GetRequiredService<SessionRegistry>();
-        fixture.TerminalHost.Registry = registry;
-        var session = registry.Create("Shell", DateTimeOffset.UtcNow);
-
-        await registry.RecordOutputAsync(session.SessionId, "primary", CancellationToken.None);
-        await registry.RecordOutputAsync(session.SessionId, "\u001b[?1049halt", CancellationToken.None);
-
-        using WebSocket socket = await fixture.Server.CreateWebSocketClient().ConnectAsync(
-            new Uri($"ws://localhost/ws/terminal?sessionId={session.SessionId}"),
-            CancellationToken.None);
-
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        var screenSnapshotFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var screenSnapshotPayload = JsonSerializer.Deserialize<TerminalScreenSnapshotResponse>(
-            screenSnapshotFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-
-        Assert.NotNull(screenSnapshotPayload);
-        Assert.Equal("alternate", screenSnapshotPayload!.ActiveBuffer);
-        Assert.StartsWith("primary", screenSnapshotPayload.PrimaryBuffer.Viewport[0].Text, StringComparison.Ordinal);
-        Assert.NotNull(screenSnapshotPayload.AlternateBuffer);
-        Assert.StartsWith("alt", screenSnapshotPayload.AlternateBuffer!.Viewport[0].Text, StringComparison.Ordinal);
-    }
-
-    [Fact]
-    public async Task Live_Patch_Carries_Alternate_Buffer_Activation()
-    {
-        await using var fixture = new TerminalApiFixture();
-        var registry = fixture.Services.GetRequiredService<SessionRegistry>();
-        fixture.TerminalHost.Registry = registry;
-        var session = registry.Create("Shell", DateTimeOffset.UtcNow);
-
-        await registry.RecordOutputAsync(session.SessionId, "same", CancellationToken.None);
-
-        using WebSocket socket = await fixture.Server.CreateWebSocketClient().ConnectAsync(
-            new Uri($"ws://localhost/ws/terminal?sessionId={session.SessionId}"),
-            CancellationToken.None);
-
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-
-        fixture.TerminalHost.EmitOutput(session.SessionId, "\u001b[?1049hsame");
-
-        _ = await ReceiveTextAsync(socket, CancellationToken.None);
-        var patchFrame = await ReceiveTextAsync(socket, CancellationToken.None);
-        var patchPayload = JsonSerializer.Deserialize<TerminalScreenPatchResponse>(
-            patchFrame,
-            new JsonSerializerOptions(JsonSerializerDefaults.Web));
-
-        Assert.NotNull(patchPayload);
-        Assert.Equal("screen_patch", patchPayload!.Type);
-        Assert.Equal("alternate", patchPayload.ActiveBuffer);
-        Assert.Empty(patchPayload.Operations);
-    }
-
     private static async Task<string> ReceiveTextAsync(WebSocket socket, CancellationToken cancellationToken)
     {
         var buffer = new byte[4096];
@@ -622,43 +413,4 @@ public sealed class TerminalWebSocketHandlerTests
         string Chunk,
         string Type);
 
-    private sealed record TerminalScreenPatchResponse(
-        string SessionId,
-        long BaseScreenVersion,
-        long ScreenVersion,
-        long SourceSequence,
-        int Rows,
-        int Columns,
-        int CursorRow,
-        int CursorColumn,
-        bool CursorVisible,
-        string ActiveBuffer,
-        IReadOnlyList<TerminalScreenPatchOperationResponse> Operations,
-        string Type);
-
-    private sealed record TerminalScreenPatchOperationResponse(
-        string Type,
-        int StartRow,
-        IReadOnlyList<string> Lines);
-
-    private sealed record TerminalScreenSnapshotResponse(
-        string SessionId,
-        long ScreenVersion,
-        long SourceSequence,
-        int Rows,
-        int Columns,
-        int CursorRow,
-        int CursorColumn,
-        bool CursorVisible,
-        string ActiveBuffer,
-        TerminalScreenBufferResponse PrimaryBuffer,
-        TerminalScreenBufferResponse? AlternateBuffer,
-        string Type);
-
-    private sealed record TerminalScreenBufferResponse(
-        IReadOnlyList<TerminalScreenLineResponse> Viewport);
-
-    private sealed record TerminalScreenLineResponse(
-        int Index,
-        string Text);
 }
diff --git a/apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Sessions/SessionRegistryTests.cs b/apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Sessions/SessionRegistryTests.cs
index cda9351..108bccd 100644
--- a/apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Sessions/SessionRegistryTests.cs
+++ b/apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Sessions/SessionRegistryTests.cs
@@ -231,9 +231,9 @@ public class SessionRegistryTests
     }
 
     [Fact]
-    public async Task GetScreenSnapshot_Returns_Authoritative_Primary_Buffer_State()
+    public async Task Experiment_GetScreenSnapshot_Returns_Authoritative_Primary_Buffer_State()
     {
-        using var harness = SessionRegistryHarness.Create();
+        using var harness = SessionRegistryHarness.Create(enableBackendScreenProtocol: true);
         var session = harness.Registry.Create("Shell", DateTimeOffset.UtcNow);
 
         await harness.Registry.RecordResizeAsync(session.SessionId, 40, 10, CancellationToken.None);
@@ -284,7 +284,9 @@ public class SessionRegistryTests
 
         public SessionRegistry Registry { get; }
 
-        public static SessionRegistryHarness Create(int lineLimit = 4000)
+        public static SessionRegistryHarness Create(
+            int lineLimit = 4000,
+            bool enableBackendScreenProtocol = false)
         {
             var dataRoot = Path.Combine(Path.GetTempPath(), "TermRemoteCtl.Tests", Guid.NewGuid().ToString("N"));
             Directory.CreateDirectory(dataRoot);
@@ -293,6 +295,7 @@ public class SessionRegistryTests
             {
                 DataRoot = dataRoot,
                 RingBufferLineLimit = lineLimit,
+                EnableBackendScreenProtocol = enableBackendScreenProtocol,
             });
             var historyStore = new SessionHistoryStore(dataRoot);
             var journalStore = new SessionIoJournalStore(dataRoot);
diff --git a/apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Terminal/TerminalScreenEngineTests.cs b/apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Terminal/TerminalScreenEngineTests.cs
index 161494e..256c63f 100644
--- a/apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Terminal/TerminalScreenEngineTests.cs
+++ b/apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Terminal/TerminalScreenEngineTests.cs
@@ -90,4 +90,46 @@ public sealed class TerminalScreenEngineTests
         Assert.Equal("primary", restoredSnapshot.ActiveBuffer);
         Assert.StartsWith("primary", restoredSnapshot.PrimaryBuffer.Viewport[0].Text, StringComparison.Ordinal);
     }
+
+    [Fact]
+    public void ApplyOutput_Osc_Window_Title_Does_Not_Leak_Into_Visible_Screen()
+    {
+        var engine = new TerminalScreenEngine(rows: 4, cols: 80);
+
+        engine.ApplyOutput("\u001b]0;C:\\WINDOWS\\system32\\WindowsPowerShell\\v1.0\\powershell.exe\u0007", sourceSequence: 1);
+        engine.ApplyOutput("PS D:\\App\\python\\MLplatform> pwd", sourceSequence: 2);
+
+        var snapshot = engine.CreateSnapshot("session-1");
+
+        Assert.DoesNotContain(
+            snapshot.PrimaryBuffer.Viewport,
+            line => line.Text.Contains("]0;", StringComparison.Ordinal));
+        Assert.DoesNotContain(
+            snapshot.PrimaryBuffer.Viewport,
+            line => line.Text.Contains("powershell.exe", StringComparison.OrdinalIgnoreCase));
+        Assert.StartsWith(
+            "PS D:\\App\\python\\MLplatform> pwd",
+            snapshot.PrimaryBuffer.Viewport[0].Text,
+            StringComparison.Ordinal);
+        Assert.Equal(0, snapshot.CursorRow);
+        Assert.Equal(32, snapshot.CursorColumn);
+    }
+
+    [Fact]
+    public void ApplyOutput_Osc_Window_Title_With_String_Terminator_Does_Not_Leak_Into_Visible_Screen()
+    {
+        var engine = new TerminalScreenEngine(rows: 4, cols: 80);
+
+        engine.ApplyOutput("\u001b]0;PowerShell Title\u001b\\", sourceSequence: 1);
+        engine.ApplyOutput("prompt> ", sourceSequence: 2);
+
+        var snapshot = engine.CreateSnapshot("session-1");
+
+        Assert.DoesNotContain(
+            snapshot.PrimaryBuffer.Viewport,
+            line => line.Text.Contains("PowerShell Title", StringComparison.Ordinal));
+        Assert.StartsWith("prompt> ", snapshot.PrimaryBuffer.Viewport[0].Text, StringComparison.Ordinal);
+        Assert.Equal(0, snapshot.CursorRow);
+        Assert.Equal(8, snapshot.CursorColumn);
+    }
 }
diff --git a/docs/superpowers/plans/2026-04-10-terminal-truth-source-reset.md b/docs/superpowers/plans/2026-04-10-terminal-truth-source-reset.md
new file mode 100644
index 0000000..d297c9b
--- /dev/null
+++ b/docs/superpowers/plans/2026-04-10-terminal-truth-source-reset.md
@@ -0,0 +1,99 @@
+# Terminal Truth-Source Reset Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Reset the terminal architecture so the mainline uses a single rendering truth source, while isolating backend-authoritative screen recovery into an explicit experiment path.
+
+**Architecture:** Keep backend journal, restore, and output as the durable data path; keep frontend `xterm` as the visible rendering path; remove backend screen protocol from the default runtime path; quarantine the backend screen engine and related protocol into an experiment track.
+
+**Tech Stack:** ASP.NET Core minimal APIs, C#, Flutter, xterm, websocket_channel, Flutter widget tests, .NET unit tests, Markdown specs and plans.
+
+---
+
+### Task 1: Lock The Mainline Runtime Boundary With Failing Frontend Tests
+
+**Files:**
+- Modify: `apps/mobile_app/test/widget_test.dart`
+- Modify: `apps/mobile_app/test/features/terminal/terminal_page_input_test.dart`
+- Test: `apps/mobile_app/test/widget_test.dart`
+- Test: `apps/mobile_app/test/features/terminal/terminal_page_input_test.dart`
+
+- [ ] **Step 1: Add a failing widget test that proves `TerminalPage` ignores backend `screen_snapshot` by default and still renders legacy `restore` content**
+- [ ] **Step 2: Add or update a widget test that proves backend screen protocol only affects rendering when explicitly enabled**
+- [ ] **Step 3: Run `C:\\tools\\flutter\\bin\\flutter.bat test test/widget_test.dart --plain-name "screen snapshot"` from `apps/mobile_app` and confirm the new expectations fail before the implementation change**
+- [ ] **Step 4: Run `C:\\tools\\flutter\\bin\\flutter.bat test test/features/terminal/terminal_page_input_test.dart` to verify the terminal input baseline remains intact before refactoring**
+
+### Task 2: Remove Backend Screen Protocol From The Default Mobile Path
+
+**Files:**
+- Modify: `apps/mobile_app/lib/features/terminal/terminal_page.dart`
+- Modify: `apps/mobile_app/lib/features/terminal/terminal_session_coordinator.dart`
+- Modify: `apps/mobile_app/lib/features/terminal/terminal_socket_session.dart`
+- Modify: `apps/mobile_app/test/widget_test.dart`
+
+- [ ] **Step 1: Add an explicit runtime flag on `TerminalPage` and `TerminalSessionCoordinator` so backend screen protocol is disabled on the default app path**
+- [ ] **Step 2: Ensure the default runtime path subscribes only to `restore` and `output` as rendering truth**
+- [ ] **Step 3: Keep screen protocol callbacks available only for explicit experiment wiring**
+- [ ] **Step 4: Re-run `C:\\tools\\flutter\\bin\\flutter.bat test test/widget_test.dart --plain-name "screen snapshot"` and confirm the default-path tests pass**
+- [ ] **Step 5: Re-run `C:\\tools\\flutter\\bin\\flutter.bat test test/features/terminal/terminal_page_input_test.dart` and confirm input behavior still passes**
+
+### Task 3: Strip Mainline Rendering Dependency On Screen Models
+
+**Files:**
+- Modify: `apps/mobile_app/lib/features/terminal/terminal_page.dart`
+- Modify: `apps/mobile_app/lib/features/terminal/terminal_screen_snapshot.dart`
+- Modify: `apps/mobile_app/lib/features/terminal/terminal_screen_state.dart`
+- Modify: `apps/mobile_app/test/features/terminal/terminal_screen_state_test.dart`
+
+- [ ] **Step 1: Remove any mainline rendering assumptions that convert backend screen models into replay text for `xterm`**
+- [ ] **Step 2: Keep screen-model helpers only if they are clearly marked as experiment-only and are no longer part of the default runtime path**
+- [ ] **Step 3: Drop or relocate tests that currently validate screen-model replay as mainline terminal behavior**
+- [ ] **Step 4: Run the targeted Flutter tests that still belong to the mainline and confirm no mainline test depends on backend screen snapshot replay**
+
+### Task 4: Simplify Backend Mainline Websocket Contract
+
+**Files:**
+- Modify: `apps/windows_agent/src/TermRemoteCtl.Agent/Realtime/TerminalWebSocketHandler.cs`
+- Modify: `apps/windows_agent/src/TermRemoteCtl.Agent/Sessions/SessionRegistry.cs`
+- Modify: `apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalWebSocketHandlerTests.cs`
+
+- [ ] **Step 1: Add failing backend tests that define the stable mainline websocket contract as `attached + restore + output`**
+- [ ] **Step 2: Remove default runtime emission of `screen_snapshot`, `screen_patch`, and `screen_sync` from the mainline websocket flow, or gate them behind an explicit experiment switch**
+- [ ] **Step 3: Keep sequence-aware `restore` and `output` semantics intact**
+- [ ] **Step 4: Run `dotnet test apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/TermRemoteCtl.Agent.IntegrationTests.csproj --filter "TerminalWebSocketHandlerTests"` and verify the stable contract passes**
+
+### Task 5: Isolate Backend Screen Engine Into An Experiment Track
+
+**Files:**
+- Modify: `apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenEngine.cs`
+- Modify: `apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenPatch.cs`
+- Modify: `apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/Terminal/TerminalScreenEngineTests.cs`
+- Modify: `docs/superpowers/specs/2026-04-10-terminal-truth-source-reset-design.md`
+
+- [ ] **Step 1: Stop treating `TerminalScreenEngine` as a production-ready mainline dependency**
+- [ ] **Step 2: Rename, relocate, or clearly annotate screen-engine code and tests as experiment-only**
+- [ ] **Step 3: Keep the experiment test suite runnable in isolation, but do not let it define default product behavior**
+- [ ] **Step 4: Run `dotnet test apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/TermRemoteCtl.Agent.Tests.csproj --filter "TerminalScreenEngineTests"` and verify the experiment suite remains green in isolation**
+
+### Task 6: Clean Up Docs And Developer Guidance
+
+**Files:**
+- Modify: `docs/superpowers/specs/2026-04-10-terminal-truth-source-reset-design.md`
+- Modify: `docs/testing/manual-smoke-checklist.md`
+- Modify: `README.md`
+
+- [ ] **Step 1: Document that the stable product path is `restore/output + xterm`, not backend screen snapshots**
+- [ ] **Step 2: Document that backend-authoritative screen recovery is an experiment branch concern**
+- [ ] **Step 3: Update manual smoke checks to focus the mainline on stable shell input, reconnect, resize, and repeated command execution**
+- [ ] **Step 4: Add a short note in `README.md` or a developer-facing doc explaining the single-truth-source rule**
+
+### Task 7: Final Verification
+
+**Files:**
+- Verify only
+
+- [ ] **Step 1: Run `C:\\tools\\flutter\\bin\\flutter.bat test test/widget_test.dart test/features/terminal/terminal_page_input_test.dart` from `apps/mobile_app`**
+- [ ] **Step 2: Run `dotnet test apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/TermRemoteCtl.Agent.IntegrationTests.csproj --filter "TerminalWebSocketHandlerTests"`**
+- [ ] **Step 3: Run `dotnet test apps/windows_agent/tests/TermRemoteCtl.Agent.Tests/TermRemoteCtl.Agent.Tests.csproj --filter "TerminalScreenEngineTests"` only as experiment verification, not as a mainline gate**
+- [ ] **Step 4: Perform a manual smoke check with `pwd -> ls -> pwd`, reconnect once, resize once, and verify the prompt remains usable**
+- [ ] **Step 5: Summarize the final boundary in release notes or task output: mainline is stable-shell-first, experiment branch is backend-screen-first**
diff --git a/docs/superpowers/specs/2026-04-10-terminal-truth-source-reset-design.md b/docs/superpowers/specs/2026-04-10-terminal-truth-source-reset-design.md
new file mode 100644
index 0000000..f0e02ec
--- /dev/null
+++ b/docs/superpowers/specs/2026-04-10-terminal-truth-source-reset-design.md
@@ -0,0 +1,275 @@
+# Terminal Truth-Source Reset Design
+
+## Goal
+
+Stop the terminal from drifting into unusable state by resetting the architecture to a single rendering truth source on the mainline, while isolating backend-authoritative screen recovery into an explicit experiment branch.
+
+## Decision
+
+The mainline must use:
+
+- frontend `xterm` as the only terminal rendering truth
+- backend journal and websocket output as the only terminal data truth
+- local mobile snapshot as a speed-only cache
+
+The mainline must not use:
+
+- backend `screen_snapshot` as a rendering truth
+- backend `screen_patch` as a rendering truth
+- frontend replay of backend screen models back into `xterm`
+
+The backend-authoritative screen protocol stays in the repository only as an experiment and must not remain on the default product path.
+
+## Why This Reset Is Necessary
+
+The current system mixes two incompatible terminal architectures:
+
+1. `xterm`-driven rendering
+2. backend screen-model-driven rendering
+
+Each one can work if it is the only truth source. They break when both are live at the same time.
+
+Today the project has all of the following active or partially active:
+
+- backend raw output journal
+- backend replay buffer
+- backend pending input echo tracker
+- backend screen engine
+- websocket `restore`
+- websocket `output`
+- websocket `screen_snapshot`
+- websocket `screen_patch`
+- frontend local snapshot
+- frontend `xterm`
+
+That creates multiple answers to the same business question:
+
+`What should the user see on screen right now?`
+
+As soon as reconnect, resize, delayed echo, PowerShell control sequences, or prompt line editing show up, the answers diverge.
+
+## Root Cause
+
+### Business View
+
+Users do not care whether reconnect shows something plausible. They care whether the terminal remains stable:
+
+- the prompt stays readable
+- typed input appears where expected
+- later commands do not corrupt earlier output
+- reconnect does not make the session less trustworthy
+
+The current design fails that because the product lets two different models of the terminal race to control the same screen.
+
+### Technical View
+
+The current backend screen engine is not strong enough to own rendering truth:
+
+- it only supports a narrow subset of escape semantics
+- it does not model scroll behavior correctly for a real shell stream
+- it does not model PowerShell line editing, prompt redraw, or table layout with enough fidelity
+- it still leaks some terminal control semantics into visible text unless patched case by case
+
+At the same time, the frontend is already using `xterm`, which is itself a terminal interpreter. Feeding backend screen state back into `xterm` means the system interprets terminal state twice.
+
+That is the structural reason the output gets more chaotic over time.
+
+## Mainline Architecture
+
+### Rendering Truth
+
+Mainline rendering truth is:
+
+- websocket `output` frames
+- websocket `restore`
+- local provisional snapshot until backend restore arrives
+- `xterm` buffer as the actual visible state
+
+This means:
+
+- the backend does not send a screen model that the frontend treats as authoritative
+- the frontend does not try to reconstruct a backend screen model on top of `xterm`
+- reconnect correctness is limited to shell-oriented restore, not full terminal-state recovery
+
+That limitation is acceptable on the mainline because stability is more important than partial fidelity masquerading as correctness.
+
+### History Truth
+
+Mainline history truth remains:
+
+- backend journal and sequence model
+- backend history API built from durable journal data
+
+This stays because it is already aligned with the right authority boundary:
+
+- journal answers `what happened`
+- `xterm` answers `what is visible now`
+
+### Local Snapshot Role
+
+Local mobile snapshot remains allowed only as:
+
+- a same-device startup acceleration layer
+- a provisional paint while waiting for backend restore
+
+It must never override backend restore correctness.
+
+## What Stays On The Mainline
+
+### Backend
+
+Keep:
+
+- `SessionIoJournalStore`
+- `SessionHistoryStore`
+- durable session journal APIs
+- sequence-aware `restore`
+- sequence-aware `output`
+- `PendingInputEchoTracker` only as part of shell-oriented restore
+- `TerminalReplayBuffer` only as part of shell-oriented restore
+
+Keep these files on the product path:
+
+- `apps/windows_agent/src/TermRemoteCtl.Agent/History/SessionIoJournalStore.cs`
+- `apps/windows_agent/src/TermRemoteCtl.Agent/History/SessionHistoryStore.cs`
+- `apps/windows_agent/src/TermRemoteCtl.Agent/Sessions/SessionRegistry.cs`
+- `apps/windows_agent/src/TermRemoteCtl.Agent/Realtime/TerminalWebSocketHandler.cs`
+- `apps/windows_agent/src/TermRemoteCtl.Agent/Sessions/SessionRestoreSnapshot.cs`
+
+### Frontend
+
+Keep:
+
+- `TerminalSocketSession` attach, restore, output handling
+- `TerminalSessionCoordinator` reconnect, pending input buffering, history browsing
+- `TerminalPage` live output rendering through `xterm`
+- local snapshot storage and restore
+
+Keep these files on the product path:
+
+- `apps/mobile_app/lib/features/terminal/terminal_socket_session.dart`
+- `apps/mobile_app/lib/features/terminal/terminal_session_coordinator.dart`
+- `apps/mobile_app/lib/features/terminal/terminal_page.dart`
+- `apps/mobile_app/lib/features/terminal/terminal_snapshot.dart`
+- `apps/mobile_app/lib/features/terminal/terminal_snapshot_storage.dart`
+
+## What Must Be Removed From The Mainline
+
+These behaviors must be removed from default runtime behavior:
+
+- frontend rendering based on `screen_snapshot`
+- frontend rendering based on `screen_patch`
+- frontend conversion of backend screen models into escape replay strings
+- backend attach contract that expects the client to consume both `restore` and `screen_snapshot` as active truths
+- backend live contract that expects the client to consume both `output` and `screen_patch` as active truths
+
+These files or code paths should no longer participate in the default product path:
+
+- `apps/mobile_app/lib/features/terminal/terminal_screen_snapshot.dart`
+- `apps/mobile_app/lib/features/terminal/terminal_screen_patch.dart`
+- `apps/mobile_app/lib/features/terminal/terminal_screen_state.dart`
+- screen-protocol branches inside `terminal_page.dart`
+- screen-protocol branches inside `terminal_session_coordinator.dart`
+- screen-protocol parsing that is wired into the default runtime path inside `terminal_socket_session.dart`
+
+## What Moves To The Experiment Branch
+
+The backend-authoritative screen effort should continue only behind an explicit experiment boundary.
+
+That experiment branch owns:
+
+- `TerminalScreenEngine`
+- `TerminalScreenSnapshot`
+- `TerminalScreenPatch`
+- websocket `screen_snapshot`
+- websocket `screen_patch`
+- websocket `screen_sync`
+- frontend screen snapshot and patch models
+- frontend screen snapshot and patch application
+
+These files belong to the experiment track:
+
+- `apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenEngine.cs`
+- `apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenSnapshot.cs`
+- `apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/Screen/TerminalScreenPatch.cs`
+- `apps/mobile_app/lib/features/terminal/terminal_screen_snapshot.dart`
+- `apps/mobile_app/lib/features/terminal/terminal_screen_patch.dart`
+- `apps/mobile_app/lib/features/terminal/terminal_screen_state.dart`
+
+The experiment is valid only if it eventually reaches this architecture:
+
+- backend owns a real terminal emulator
+- frontend does not feed screen models back into `xterm`
+- frontend renders screen state directly from backend screen data
+
+If that condition is not met, the experiment should not merge back into mainline.
+
+## Runtime Boundary
+
+There must be an explicit runtime boundary between:
+
+- stable mainline behavior
+- experimental screen-protocol behavior
+
+Recommended rule:
+
+- mainline build defaults `enableBackendScreenProtocol = false`
+- experiment branch may enable it by explicit wiring
+- no hidden fallback should silently re-enable screen protocol in production paths
+
+## Testing Strategy
+
+### Mainline Tests
+
+Mainline tests should prove:
+
+- `pwd -> ls -> pwd` remains stable
+- reconnect keeps input working
+- resize does not corrupt future input
+- output remains append-oriented and readable through `xterm`
+- local snapshot is provisional and restore remains authoritative
+
+Mainline tests must not assert backend screen snapshot correctness.
+
+### Experiment Tests
+
+Experiment tests should prove:
+
+- scroll semantics
+- cursor-addressed redraw
+- PowerShell title or control sequences
+- prompt editing
+- alternate buffer behavior
+- screen version continuity
+
+These tests should not block mainline unless the experiment is being promoted.
+
+## Migration Plan
+
+### Phase 1: Mainline Reset
+
+- disable screen protocol on the default mobile path
+- stop using backend screen models to drive visible terminal state
+- keep journal, restore, output, and local snapshot semantics intact
+- remove or quarantine tests that assume backend screen protocol is part of default production behavior
+
+### Phase 2: Codebase Cleanup
+
+- remove dead mainline branches for screen protocol
+- move screen protocol files and tests under an explicit experiment area or keep them feature-gated with clear naming
+- update docs so the team cannot mistake the experiment for the product path
+
+### Phase 3: Experiment Continuation
+
+- continue backend-authoritative screen work in isolation
+- do not merge until the frontend rendering model also changes
+
+## Acceptance Criteria
+
+This reset is complete when:
+
+- the default app path no longer consumes `screen_snapshot` or `screen_patch`
+- terminal rendering uses only one truth source on the mainline
+- repeated shell commands do not progressively corrupt the visible prompt
+- reconnect and resize no longer activate competing rendering paths
+- the repository documents that backend-authoritative screen recovery is experimental, not production truth
diff --git a/docs/testing/manual-smoke-checklist.md b/docs/testing/manual-smoke-checklist.md
index 337fbcb..6d50ef9 100644
--- a/docs/testing/manual-smoke-checklist.md
+++ b/docs/testing/manual-smoke-checklist.md
@@ -3,11 +3,14 @@
 1. Start the Windows agent on the primary Windows machine.
 2. Pair the iPhone app with a fresh one-time pairing code.
 3. Create `codex-main` and `cloud-code` sessions.
-4. Start a noisy command in `codex-main`.
-5. Background the app for one minute.
-6. Reopen the app and confirm the same session is still alive.
-7. Scroll upward and confirm older history loads.
-8. Trigger one preset command and confirm it appears in the terminal.
-9. Terminate one session and confirm only that session exits.
-10. Type a partial command, background the app, reopen it, and confirm the typed command is still visible.
-11. Execute a command, reconnect during output, and confirm the command is not duplicated after restore.
+4. In `codex-main`, run `pwd`, then `ls`, then `pwd` again and confirm the prompt stays readable.
+5. Start a noisy command in `codex-main` and confirm live output keeps appending in the terminal view.
+6. Background the app for one minute.
+7. Reopen the app and confirm the same session is still alive and input still works.
+8. Type a partial command, background the app, reopen it, and confirm the typed command is still visible after restore.
+9. Resize the terminal once and confirm later input still appears in the expected prompt position.
+10. Scroll upward and confirm older history loads without corrupting the live terminal.
+11. Trigger one preset command and confirm it appears in the terminal.
+12. Terminate one session and confirm only that session exits.
+13. Execute a command, reconnect during output, and confirm the command is not duplicated after restore.
+14. Confirm the mainline terminal stays driven by `restore + output + xterm`; do not use backend `screen_snapshot` or `screen_patch` as the visible truth.